Modular rapid development system for building underwater robots and robotic vehicles

ABSTRACT

A modular system for building underwater robotic vehicles (URVs), including a pressure vessel system, modular chassis elements, a propulsion system and compatible buoyancy modules. The pressure vessel system uses standardized, interchangeable modules to allow for ease of modification of the URV and accommodation of different internal and external components such as sensors  4800  and computer systems. The system also includes standard, reconfigurable connections of the pressure vessel to the modular chassis system. A standardized, modular propulsion system includes a magnetic clutch, and a magnetic sleeve used to power the URV on or off.

This application is a continuation of U.S. application Ser. No.14/495,799, filed Sep. 24, 2014, for MODULAR RAPID DEVELOPMENT SYSTEMFOR BUILDING UNDERWATER ROBOTS AND ROBOTIC VEHICLES which claims thebenefit of U.S. Provisional Application No. 61/881,894, filed Sep. 24,2013, for MODULAR RAPID DEVELOPMENT SYSTEM FOR BUILDING UNDERWATERROBOTS AND ROBOTIC VEHICLES, which is incorporated in its entiretyherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to autonomous underwater robots,and more specifically, to systems and methods for building autonomousunderwater robots and remotely piloted underwater robotic vehicles

2. Discussion of the Related Art

Just as robotic vehicles have proven their effectiveness as analternative to manned space exploration, researchers in Oceanography,Sub-Sea Oil and Gas and Mineral Production, Fisheries Management, MarineEnvironmental Pollution Management, Marine Biological Diversity Surveys,Marine Salvage, Underwater Search and Rescue, and other related fieldshave found underwater robotic vehicles an effective alternative tosending divers into the water.

Several companies manufacture underwater robotic systems. The primaryusers of these robots are the sub-sea oil and gas companies, whoseprofits may justify the robots' high cost. The largest of the marinescience institutions such as Scripps Oceanographic Institution, MontereyBay Aquarium Research Institute, Woods Hole Oceanographic Institute, aswell as large governmental agencies such as the National Oceanic andAtmospheric Administration (NOAA) also employ such vehicles for deepocean research, although in far smaller numbers than in the oil field.The typical high prices reflect their high performance, providingreliable maneuverability, video tele-presence, and ability to manipulateconstruction tools sometimes thousands of feet below the ocean surfaceunder some of the harshest environmental conditions on earth.

A few companies make relatively low performance systems for a muchsmaller cost, and many of these are used by municipal search and rescueteams, or for sub-surface ship inspection and other less demandingshallow water tasks. But even at the “low end” those commercialunderwater robotic systems exceed the budgets of the majority ofpotential users of underwater robotic systems.

A second problem exists for these potential users. The least expensiveof the commercial systems tend to be single purpose vehicles of verysimple design and thus the least flexible in terms of configuration.Many researchers require vehicles with more options for attachinginstrument payloads, different cameras, more thruster characteristics,etc., than are present in any commercial systems they can afford. But nocommercially available Underwater Robotic System offers its usersfreedom of choice, at a modular level, over the mechanical configurationof their system (e.g., how many thrusters for degrees of freedom oflocomotion), what computational hardware to control the system (e.g., afull-function Intel-based computer running either Windows or Linux or asmall 8 or 16-bit microcontroller) and whether that processor isprogrammed in C, Java, Python, or another language. Changing any ofthese would usually mean switching manufacturers or buying a secondsystem to fit the new requirements. No inexpensive ‘build-by-menu andreconfigure-at-will’ underwater robotic solution exists for those whoneed broad freedom in design and configuration.

As a result, most potential users of underwater tele-presence robots whoneed a cheap, simple, easily re-configured system must currently designand build their own underwater robotic system from scratch; this isdifficult for even experienced researchers and usually prohibitively sofor the inexperienced. While such a do-it-yourself method allows thesystem to be tailored exactly to the mission requirements at hand, costscan easily exceed the those of a comparable commercial system whendesign and test time spent dealing with the inadequacies of a leaky,unreliable prototype are factored in. And unless modularity,extendibility, and re-configurability are carefully thought out anddesigned into the prototype, these scratch-built systems usually fail toprovide the flexibility for expansion and re-configuration that the userwill soon wish for to meet new performance requirements or to attach newpayloads.

SUMMARY OF THE INVENTION

Several embodiments of the invention advantageously address the needsabove as well as other needs by providing an underwater pressure vesselsystem, comprising: a dry end cap comprising a generally cylindricalinternal portion including at least one groove extending around aperimeter of the cylindrical body, the at least one groove locatedproximate to a first end of the dry end cap configured for receiving ano-ring seal; at least one o-ring seal coupled to the cylindrical bodyand seated in the at least one groove; a generally cylindrical externalportion concentric to the internal portion and located distal to thefirst end, wherein a diameter of the external portion is greater thanthe diameter of the internal portion, and wherein the end of theexternal portion distal to the internal portion is a second end of thedry end cap; a plurality of component mounting holes included in thefirst end of the internal portion, the component mounting holes arrayedin a circle proximate to the perimeter of the internal portion andoriented parallel to a longitudinal axis of the connection module, thecomponent mounting holes configured for coupling of a component to theconnection module; a plurality of link strut mounting holes including inthe external portion of the connection module, the link strut mountingholes arrayed around a perimeter of the external portion and orientedradially with respect to the external portion, the link strut mountingholes configured to couple to a link strut; and a plurality of tubemounting holes arrayed around the perimeter of the internal portion,oriented radially with respect to the internal portion, and locatedbetween the at least one o-ring and the external portion, wherein theplurality of tube mounting holes are configured for coupling to apressure vessel tube.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of severalembodiments of the present invention will be more apparent from thefollowing more particular description thereof, presented in conjunctionwith the following drawings.

FIG. 1 is a perspective view of an exemplary Underwater Robotic Vehicle(URV) as constructed in accordance with an Underwater Robotic VehicleDevelopment System (URVDS).

FIG. 2 is a perspective view of a URV chassis in one embodiment of thepresent invention.

FIG. 3 is a perspective view of a light-duty rail clamp.

FIG. 4 is a perspective view of a heavy-duty rail clamp.

FIG. 5 is a perspective view of a pressure vessel coupled to rails vialink struts.

FIG. 6 is a perspective view of a portion of the chassis.

FIG. 7 is an elevational end-view of an exemplary URV systemsuperimposed on a chassis grid geometry.

FIG. 8 is an elevational end-view of an exemplary two-frame chassiscoupled to two differently-sized pressure vessel.

FIG. 9 is a perspective view of an exemplary non-orthogonal heavy-dutychassis configuration.

FIG. 10 is a perspective view of an exemplary URV including theheavy-duty chassis.

FIG. 11 is a perspective view of an exemplary pressure vessel inaccordance with one embodiment of the invention.

FIG. 12 is a perspective view of another exemplary pressure vessel inaccordance with a further embodiment of the invention.

FIG. 13 is a perspective view of a side of the dry end cap.

FIG. 14 is a perspective view of an internal end of the dry end cap.

FIG. 15 is a perspective view of a pressure vessel tube in oneembodiment of the present invention.

FIG. 16 is a perspective view of a reinforcement collar coupled to thetube.

FIG. 17 is a cross-sectional view of a reinforcement collar coupled tothe tube.

FIG. 18 is a perspective view of an external end of the dry end cap.

FIG. 19 is an exploded cross-sectional view of one embodiment of the dryend cap with a mounting rim.

FIG. 20 is a perspective view of an end cap collar in one embodiment ofthe present invention.

FIG. 21 is a cross-sectional view of a first dry end cap and a seconddry end cap coupled together via the mounting rim and the end capcollar.

FIG. 22 is a perspective view of the dry link module.

FIG. 23 is a perspective view of a cable manifold link in one embodimentof the present invention.

FIG. 24 is a perspective view of the cable manifold link showing aninterior of the cable manifold link.

FIG. 25 is a cross-sectional view of a cable manifold dry end cap.

FIG. 26 is a perspective view of a central pressure vessel including thecable manifold link with attached auxiliary pressure vessel.

FIG. 27 is a perspective view of a dry nosecone in one embodiment of thepresent invention.

FIG. 28 is a perspective view of a floating pressure vessel wall.

FIG. 29 is a perspective view of a pressure vessel wall support columnin one embodiment of the present invention.

FIG. 30 is a perspective view of a tube portion of the pressure vesselincluding two floating pressure vessel walls and a support column.

FIG. 31 is a perspective exploded view of a wet link and mounting rim inone embodiment of the present invention.

FIG. 32 is a perspective view of a wet nosecone in one embodiment of thepresent invention.

FIG. 33 is a perspective view of a deck mounting rim in one embodimentof the present invention.

FIG. 34 is a perspective view of the deck mounting rim coupled to thedry end cap.

FIG. 35 is a perspective view of pressure vessel coupled to a deck usingthe deck mounting rims.

FIG. 36 is a perspective view of pressure vessel coupled to a deck usingthe deck mounting rims.

FIG. 37 is an exploded view of a plurality of circular PCBs is shown formounting to the dry end cap.

FIG. 38 is a perspective view of a rectangular PCB mounting bracket inone embodiment of the present invention.

FIG. 39 is a perspective view of a plurality of rectangular PCBs mountedto the dry end cap.

FIG. 40 is an exploded view of a rectangular PCB mounting shelf andmounting plate.

FIG. 41 is a perspective view of rectangular PCBs coupled to the drynosecone using the mounting shelf and the mounting plate.

FIG. 42 is a perspective view of a mounting clip in a first embodiment.

FIG. 43 is a perspective view of the mounting clip in a secondembodiment.

FIG. 44 is a perspective view of a generic mounting plate with mountingclips.

FIG. 45 is a perspective view of an exemplary coupling of rectangularPCBs to the support column using the mounting clips.

FIG. 46 is a perspective view of an exemplary pressure vessel system inaccordance to one embodiment of the invention.

FIG. 47 is a schematic diagram of an exemplary electrical andcommunication system for the URVDS.

FIG. 48 is a perspective view of the cable manifold link includingdirectly connecting sensors.

FIG. 49 is a cross-sectional view of the dry end cap including a sensorcable port.

FIG. 50 is an exploded cross-sectional view of the dry end cap includinga sensor hole in one embodiment of the invention.

FIG. 51 is a perspective view of a power management system coupled tothe dry end cap.

FIG. 52 is a schematic electrical circuit diagram for the powermanagement system.

FIG. 53 is a perspective view of the pressure vessel including amagnetic switch sleeve in a first location.

FIG. 54 is a perspective view of the pressure vessel including themagnetic switch sleeve in a second location.

FIG. 55 is a perspective view of the pressure vessel including themagnetic switch sleeve in a third location.

FIG. 56 is a perspective view of the pressure vessel including anexternal power and charging port.

FIG. 57 is a perspective view of an exemplary URV including a sixdegree-of-freedom propulsion system.

FIG. 58 is an exploded perspective view of an exemplary thruster motorand coupling.

FIG. 59 is a perspective view of a magnetic clutch end cap.

FIG. 60 is a cross-sectional view of the magnetic clutch end cap coupledto a propeller module.

FIG. 61 is an exploded view of a portion of an inline thruster pressurevessel.

FIG. 62 is an elevational view of the portion of the inline thrusterpressure vessel.

FIG. 63 is an elevational view of a portion of a lateral thrusterpressure vessel.

FIG. 64 is a cross-sectional view of a lateral propeller module.

FIG. 65 is an elevational view of a portion of an inline rudder thrusterpressure vessel.

FIG. 66 is a cross-sectional view of the portion of the inline rudderthruster pressure vessel.

FIG. 67 is a cross-sectional view of a rudder shaft mount.

FIG. 68 is a perspective view of a cylindrical float buoyancy module.

FIG. 69 is a perspective view of an exemplary URV including a syntacticfoam buoyancy module.

FIG. 70 is a perspective view of a ballast module.

FIG. 71 is a perspective view of ballast modules coupled to the URVchassis.

FIG. 71A is a first elevational view of the underwater URV.

FIG. 71B is a second elevational view of the underwater URV.

FIG. 71C is a third elevational view of the underwater URV.

FIG. 71D is a fourth elevational view of the underwater URV.

FIG. 72 is a perspective view of a plurality of exemplary URVs.

FIG. 73 is a perspective view of an exemplary three-cell URV.

FIG. 74 is a perspective view of an exemplary small-scale URV.

FIG. 75 is a perspective view of an exemplary pipe inspection URV.

FIG. 76 is a perspective view of an exemplary heavy-lift salvage URV.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousembodiments of the present invention. Also, common but well-understoodelements that are useful or necessary in a commercially feasibleembodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but ismade merely for the purpose of describing the general principles ofexemplary embodiments. The scope of the invention should be determinedwith reference to the claims.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

Furthermore, the described features, structures, or characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. In the following description, numerous specific details areprovided, such as examples of programming, software modules, userselections, network transactions, database queries, database structures,hardware modules, hardware circuits, hardware chips, etc., to provide athorough understanding of embodiments of the invention. One skilled inthe relevant art will recognize, however, that the invention can bepracticed without one or more of the specific details, or with othermethods, components, materials, modules, and so forth. In otherinstances, well-known structures, materials, or operations are not shownor described in detail to avoid obscuring aspects of the invention.

It will be appreciated that the present disclosure and drawings describeand depict one or more preferred embodiments of an actual workingvehicle configuration that has been built with the system. Wheredimensions are provided, the dimensions referred to are those of theactual components used in the one or more exemplary embodimentsdisclosed herein. It will be appreciated that many other configurationsare possible within the scope of this disclosure.

Referring first to FIG. 1, an exemplary Underwater Robotic Vehicle (URV)100 as constructed in accordance with a Underwater Robotic VehicleDevelopment System (URVDS) is shown. Shown are a chassis 102, aplurality of pressure vessels 104, a plurality of thruster pressurevessels 106, and a plurality of buoyancy modules 108.

The exemplary URV 100 comprises the structural chassis 102, which istypically constructed in an open framework configuration. In oneembodiment, the chassis 102 comprises elements of a modular chassissystem described further below. The pressure vessels 104, buoyancymodules 108, and other elements of the URV 100 are coupled to andsupported by the chassis 102. The pressure vessels 104 comprise thefunctional systems of the URV 100, and may include electrical systems,internal support architecture, propulsion systems, and systems forcoupling peripheral components to the URV 100. The pressure vessels 104,buoyancy modules 108 and additional URV components are described furtherbelow.

The URVDS as described herein serves to simplify and speed up the designprocess for those who need to build a variety of reliable, low-costunderwater robotic vehicles. In one form, the URVDS is an“erector-set”-like construction set of modular elements and methods forbuilding underwater robots that includes two features. The first featureis the chassis system, a set of modular structural elements for rapidlyassembling the chassis 102 for the URV 100 in a systematic, coherent,and extensible way in accordance with standardized form factors. Usingor building chassis modules in adherence with the form factors laid outin a chassis geometry grid convention ensures trouble-free mechanicalinterconnection and interoperability with existing chassis modules,allowing easy expansion of the system and allowing new chassis modulesto be shared with other users. The second feature is the pressure vesselsystem comprising a standardized set of modular elements, from a nearlyunlimited number of different URV 100 designs can be quickly assembled.Each of these components performs at least one function related to astructural assembly of URV 100 functional components onto the chassis102. These functions include, but are not limited to, reliableelectrical wiring distribution between pressure vessels 104, mountingcontrol circuitry within pressure vessels 104, or propeller thrustersfor locomotion. Typically pressure vessel modules combine one or more ofthese functions with the function of providing watertight sealing of thepressure vessel 104 assembled with the modules.

The pressure vessel and chassis systems provide the tools to quicklybuild a robust mechanical platform and reliable underwater environmentalprotection for the user's choice of the electronic components(computers, motors, sensors, etc.) around which to design their URV 100.

The URVDS provides the system of modular elements to build URVs 100 thatare fundamentally mutable in scale, complexity, and mission capability.The URVDS seamlessly integrates several systems including some knownelements and components into a unified, systematic, coherent andextensible method for constructing the URV 100.

The URVDS supports the mutability of the entire system to buildcompletely different URVs 100 is a fundamental property of each elementand component in the system. Each element and component interconnectswith others via the chassis 102 to form functional cells, and thechassis 102 supports the easy addition of additional chassis elementswith attached functional pressure vessels 104 to increase thefunctionality of the URV 100. Also, the URVDS includes a set ofarchitectural rules and dimensional standards by which other designerscan build additional chassis modules that interoperate with existingsystem chassis modules.

The URVDS is easily adapted to attachment to a non-robotic underwaterload (large instrument, camera, or heavy object to be simply moved) inorder to provide convenient mobility to the object in cases where theobject is too heavy to be easily or safely moved by divers 1004 or needsto be moved between points, either under human control or autonomously,in a more predictable and repeatable manner than human divers 1004 canprovide (such as a large format underwater camera precisely repeatingunderwater tracking shots with complex camera movements or speeds for anumber of separate ‘takes’).

The URVDS allows a builder to easily share and interchange the entiresuite of chassis modules needed to build the URV 100 with other buildersin a systematic and collaborative way, increases value and reduces costand reinvention time for all users, especially researchers whose workrequires peer review and experimental duplication and validation.

Like any robotic system, URV 100 is composed of computationalelectronics, sensors 4800, actuators, a power supply (typicallybatteries), and the chassis 102 to connect all components together. Inaddition, the URV 100 also needs means of protecting the electronicsfrom water ingress, and the URV 100 also requires some means of precisebuoyancy control and three-dimensional propulsion through water. Manyoptions for computation and control electronics exist for robotics.Hobby radio-control transmitter-receiver-servo based systems, embeddedLinux controllers, microcontroller based control solutions like Arduino™are becoming cheaper, more powerful, and becoming familiar and availableto increasingly wider numbers of users. The Hobby Radio Control Vehicleuser base drives the cost of control components, camera systems andpower components such as NiMH and Lithium Ion batteries and chargingsystems down and their power and reliability up, so that now there aremany ground and aerial robotic systems that let users reconfigure andswap the mechanical and electronic hardware systems to improveperformance or change the overall performance and mission capability oftheir robots.

But this growth in variety of vehicle choices is not echoed in low costunderwater robotics for either the underwater research user community orthe hobbyist community. While a very few inexpensive URV 100 systemsexist, they are built to one configuration, without the ability tocustomize them to different missions, mobility configurations, orcontrol systems. There are no “build-by-menu”, reconfigurable-at-will“erector-set” type construction kit systems for underwater roboticsequivalent to the many such systems for on-land or aerial (drone)robotics.

The URVDS provides those capabilities through a set of module andassociated component systems from which users can construct a widevariety of underwater robotic systems to accomplish their data gatheringtasks. The systems include the chassis system, a pressure vessel system,a printed circuit board mounting system, an electrical distributionsystem, a propulsion system, and a buoyancy management system.

In the one embodiment, the chassis system includes elements to easilyand quickly build the strong, lightweight, and easily reconfigurablechassis 102 for the URV 100, upon which all the other elements aremounted.

The pressure vessel system in one embodiment of the present inventionincludes watertight housings to contain control electronics, batteries,sensors 4800, cameras, thruster motors 5800 for locomotion, and similarcomponents necessary to the operation of the URV 100.

The electrical distribution system comprises the power system andcontrol system architecture of the URV 100.

The buoyancy system may include one or more buoyant modules coupled tothe chassis 102.

Generally, the term module is used to refer to elements used inconstructing the pressure vessels 104, including tubes 1100, end caps,links, and thruster propeller modules. The term component is used torefer to elements supported by or contained within the pressure vesselor chassis, such as cables 1214 2604, ports 2300, printed circuitboards, and sensors.

Chassis System

Referring next to FIG. 2, the URV chassis 102 in one embodiment of thecurrent invention is shown. Shown are a plurality of chassis rods 310,including rails 200, braces 202, beams 204 and posts 206. A plurality ofrail clamps 208 is also shown.

The chassis 102 is comprised of the plurality of chassis rods 310coupled together to form a three-dimensional space frame. In theembodiment shown the space frame is orthogonal in shape, but it will beappreciated by those skilled in the art that non-orthogonal systems andsystems including curved rods 310 may be constructed using the chassissystem elements shown in FIG. 2. For the chassis 102 as shown in FIG. 2,the y-direction is oriented parallel to the longitudinal axis of thechassis 102 and also to the longitudinal axes of the pressure vessel 104mounted to the chassis 102. The orthogonal x-direction forms ahorizontal plane with the y-direction, and the z-direction is defined tobe upwards from the x-y plane.

The rods 310 may be comprised of stainless steel, anodized aluminum, orany other submersible, non-corrosive material with suitable strength. Inthe present embodiment, the rods 310 include a round cross-section, butthe cross-section may be any cross-section suitable for use with therail clamp 208 connectors, the operation of which is described in moredetail below. The rods 310 may have any diameter required to supportvarious URV pressure vessels 104 and other components mounted on thechassis 102. In the present embodiment, the rail 200 diameters are ¼ ″for a light-use chassis 102 and 1″ for a heavy-use chassis 102. Otherchassis rods 202 204 206 are 3/16″ rods threaded on each end with 10-32threads. Rods 310 configured for coupling to rail clamps 208 arethreaded on each end. In another, heavy-duty embodiment, rails may be 1″in diameter and other rods 202 204 206 ¾″ in diameter.

In the chassis 102 shown in FIG. 2, six continuous rails 200 orientedparallel to the longitudinal axis of the chassis 102 (i.e. in they-direction) and extending an entire length of the chassis 102 arecoupled to perpendicular rods 310 (i.e. in the x- and z-directions) toform the space frame. Geometrical spacing of the rails 200 is describedfurther below in FIGS. 7 and 8. In the x-direction, beams 204 arecoupled to intersecting rails 200 with the rail clamps 208 threadablycoupled to each end of the beam 204. Each rail clamp 208 includes a railaperture 308 for receiving one rod 310, typically a rail 200, asdescribed below. The rail clamps 208 are configured to threadably coupleto the beam 204 (or other type of rod 310), slide over the rail 200, anddemountably clamp to the rail 200. When more than one rod 310 is coupledto the rail 200 at a single joint, the rail clamps 208 may be slightlystaggered to accommodate the multiple connections.

Beams 204 may be spaced at any dimension as required for stability andstrength of the chassis 102.

In the z-direction, vertical posts 206 are coupled to intersecting rails200 using the rail clamps 208. As with the beams 204, the posts 206 maybe spaced at any suitable dimension. In the embodiment shown, the posts206 are spaced at a dimension approximately twice the dimension betweenthe rails 200 in the x-direction. Diagonal braces 202 in the x-y, y-z orx-z planes may also be used to provide lateral stability to thestructure.

Referring again to FIG. 2, the chassis system is reconfigurable toprovide structural support for any combination of URVDS pressure vessels104 and components. The rail clamps 208 provide for pressure vessels 104that can be easily attached, detached, slid along the frame to adjustin-water balance, or repositioned or removed from the frame andrecombined into new vehicles for different purposes, as describedfurther below. This makes development of new vehicles much faster thanin current static URV 100 designs which require substantial re-design toincorporate new pressure vessels 104 and/or components, especially onesthat changes the balance enough to make the URV 100 nose-heavy ortail-heavy. By making the rails 200 the central mechanical structureupon which the URV is built, ease of addition and reconfiguration ofthrusters, computation, sensors 4800, power, buoyancy and other modulesand/or components are core features of the URVDS.

The reconfigurable chassis 102 can thus be quickly assembled whichallows the user to start mounting pressure vessels 104 and/or componentsto test various vehicle configurations and get an experimental vehicleup and running. The user can add or subtract chassis length by swappingin different rods 310 as needed, or add sections vertically orhorizontally to fit more components as needed. Once a chassis design isfinalized, the user can continue to use the reconfigurable chassis or aconstruct a permanent chassis of welded steel or aluminum. In oneembodiment, the permanent chassis may be constructed using rods 310(comprising carbon fiber, fiberglass, or other suitable material) inconjunction with pre-made corner and/or tee pieces that are coupled tothe rods 310, similarly to PVC pipe construction.

Rods 310 typically comprise either stainless steel or aluminum rodcommercially available from many sources. If aluminum is used and thechassis 102 is to be used in sea-water, the rods 310 may be anodized toinhibit corrosion. In other embodiments the rods may be other materialssuch as PVC pipe which is commonly used among amateur URV 100 builders.

The rods 310 themselves need not necessarily be solid rods. The rods maybe open tubes to reduce weight and material while retaining structuralstiffness or they may be larger diameter tubular housings for long thinelements such as batteries. The rods 310 may thus function both asstructural elements and as pressure vessel 104 provided that thestresses imposed by functioning as the chassis rod 310 do not compromiseits integrity as the pressure vessel 104.

The reconfigurable chassis system as shown in FIG. 2 allows quick andeasy reconfiguration of the chassis geometry. However, it will beappreciated that it may be desirable, once a chassis configuration isfinalized, to replace the reconfigurable chassis system with apermanent, welded configuration. Due to the greater rigidity of thewelded joints, members of the reconfigurable configuration may beeliminated in the welded configuration while still preserving thestructural capacity of the chassis 102. The welded chassis 102 may becomprised of steel, aluminum, or other suitable weldable material.

Referring next to FIG. 3, a light-duty rail clamp 400 coupled to thebeam 204 is shown in one embodiment of the present invention. Shown arethe beam 204, a light-duty rail clamp base 402, a light-duty rail clampcollar 304, and a plurality of rail clamp screws 306.

In the embodiment shown, the light-duty rail clamp base 402 includes athreaded hole configured to be threadably coupled to the threaded end ofthe beam 204. It will be understood by those of ordinary skill in theart that the rail clamp 208 may be coupled to any threaded rod 310 ofthe chassis 102. The light-duty rail clamp collar 304 is approximatelyU-shaped, with legs of the U-shape demountably coupled to a side of thelight-duty rail clamp base 402 opposite to the beam 204. In theembodiment shown, the light-duty rail clamp collar 304 is coupled to thelight-duty rail clamp base 402 using at least two clamp screws 306 thatscrew into countersunk through-holes in the legs of the light-duty railclamp collar 304. When the light-duty rail clamp collar 304 is coupledto the light-duty rail clamp base 402, the rail aperture 308 is formed.The light-duty rail clamp collar 304 is configured to provide forclamping to the desired rail 200 configuration, which in the lightchassis configuration is ¼″ in diameter. In the embodiment shown, a topedge of the rail aperture 308 is curved. The rail 200 may be slidthrough the rail aperture 308 or the light-duty rail clamp collar 304may be installed after the beam 204 and the light-duty rail clamp base402 are positioned on the rail 200. Further tightening of the clampscrews 306 frictionally locks the light-duty rail clamp 400 to the rail200. The light-duty rail clamp 400 may be moved or removed by looseningof the clamp screws 306.

Referring next to FIG. 4, a heavy-duty rail clamp 400 is shown in oneembodiment of the present invention. Shown are the beam 204, the railaperture 308, the clamp screws 306, a heavy-duty rail clamp base 402,and a heavy-duty rail clamp collar 404.

Similar to the light-duty rail clamp 400, the heavy-duty rail clamp 400comprises the heavy-duty rail clamp base 402 threadably coupled to thebeam 204, and the heavy-duty rail clamp collar 404, in a generalU-shape, with legs of the U-shape demountably coupled to the heavy-dutyrail clamp base 402. In the present embodiment, the heavy-duty railclamp 400 is configured to threadably receive the beam 204 approximately3/16″ in diameter and attach to the rail 200 approximately 1″ indiameter. The configuration and operation of the heavy-duty rail clampcollar 404 is similar to that of the light-duty rail clamp collar 304.It will be apparent to those skilled in the art that the dimensions ofthe light-duty and heavy duty rail clamps 300 400 may be modified toaccommodate alternate rail 200 s and beams 204 with alternatecross-sectional geometry and dimensions.

Referring again to FIGS. 3 and 4, the beam 204 (or other type of rod310) is threadably coupled to the clamp base using the threaded hole inthe clamp base. The clamp collar and clamp base include threaded holeson each side for receiving the clamp screws 306.

Rail clamps 208 may be comprised of stainless steel or aluminum, or anyother metal suitable for forming the rail clamp 208 shape and couplingto the rod 310.

Alternately, the rail clamp base 302 402 and the rail clamp collar 304404 may comprise different materials. Preferably, the U-shaped portion4202 of the rail clamp 208 that forms the mechanical interlock with therail 200 is oriented towards the outside of the chassis 102, andremovable via the clamp screws 306. This would ensure that the pressurevessel 104 connected to the rails 200 could be slid in and out frombetween even four rails 200 without having to separate the rails 200.This would facilitate exchange of pressure vessels 104 for test orrepair without disturbing the chassis 102 and other pressure vessels 104mounted onto it.

Additionally, a portion of the rail clamp base 302 402 that contacts therail 200 is essentially straight so that the rail clamp base 302 402 maybe removed from the rail 200 of the chassis 102 without having to movethe rail 200. If the rail clamp base were curved to receive the rail200, in order to remove the rail clamp 208 the rail 200 would have to bemoved out of the curved area. The straight rail clamp base 302 402allows the rail clamp base 302 402 to be slid away from the rail 200when the rail clamp collar 304 404 is removed.

In addition to the pressure vessels 104, other types of peripherals maybe directly mounted on the chassis 102 using the rail clamps 208. For,example, a sonar transducer module as shown may be configured to receivea link strut 500 coupled to the rail clamp 208. The rail clamp 208 maythen be removably coupled to the chassis 102 as previously described.Mounting one or more peripheral devices on rail clamps 208 allows themto be freely positioned around the URV 100 for ranging and localcollision avoidance.

Referring next to FIG. 5, the pressure vessel 104 is shown coupled tothe rails 200 via the link struts 500. Shown are the pressure vessel104, the rails 200, the rail clamps 208, and the link struts 500.

The link struts 500 are rods used to couple pressure vessels 104 orother URV components to the chassis 102. As with beams 204, posts 206and braces 202, the link strut 500 is threaded at each end. The linkstruts 500 may comprise the same material and/or geometry as the beam204, post 206 or brace 202. A first end of the link strut 500 is coupledto the rail 200 of the chassis 102 using the rail clamp 208 aspreviously described. A second end of the link strut 500 is threadablycoupled to an external threaded hole in the pressure vessel 104. Thepressure vessels 104 include the external threaded holes configured forreceiving the link strut 500, as described further below. In order toprovide stability of the pressure vessel 104, typically link struts 500are coupled to the pressure vessel 104 at an angle to at least one otherlink strut 500, relative to the longitudinal axis of the pressure vessel104.

The length and attachment angle of the link strut 500 may be variedusing a plurality of link strut mounting holes 1302 of the pressurevessel 104 to accommodate different pressure vessel 104 sizes andlocations relative to the chassis 102. The length and angle would alsostill typically conform to a chassis grid convention as describedfurther below.

Referring next to FIG. 6, a portion of the chassis 102 including aplurality of rail-to-rail truss rods 600 is shown. Shown are the rails200, the rail clamps 208, the posts 206, the beams 204, a plurality oftruss rod rail clamps 602 and the truss rods 600.

Additional diagonal truss rods 600 may be used between post 206, beam204 or brace 202 connection points. Truss rods 600 may comprise threadedrods with the rail clamp 208 coupled to each end, similar to the post206, beam 204 or brace 202 rods. The rail clamp 208 is modified toprovide for a connection to the truss rod 600 at an angle between 0-90degrees relative to the rail 200 axis (with the typical rail clamp 208providing an approximately 90 degree connection). In the exemplaryversion shown in FIG. 6, the truss rods 600 are coupled to the rails 200at an approximately 45 degree angle.

In another embodiment, the truss rod 600 includes truss rod rail clamps602 at each end of the truss rod for removable coupling of the truss rodto the rail 200. In yet another embodiment, the truss rods 600 may bepermanently welded to the rails 200. The truss rods 600 may couple tworails 200, as shown, but also may couple any two other chassis members,e.g. rail-post, post-beam, etc.

When multiple pressure vessels 104 are mounted on the chassis 102, thetriangular bracing of the link struts 500 stiffen the chassis rails 200against lateral deflections from torsion and shear, but do not offertriangular bracing against front-to-back shear, e.g., from a forwardimpact to the end of the rail 200. When needed, the truss rods 600 mayadd additional stiffness against shear.

Referring next to FIG. 7, an end-view of an exemplary URV 100 systemwith a chassis grid 700 is shown. Shown are a first pressure vessel 702,a second pressure vessel 704, a third pressure vessel 706, a fourthpressure vessel 708, a fifth pressure vessel 710, the chassis 102, thechassis grid 700, a grid unit 712, a frame height 716, a frame width 718and the plurality of link struts 500.

A chassis geometry convention system in one embodiment is based on thechassis grid 700 comprising identical equilateral triangles (60-60-60).The side length of the equilateral triangles may be revised as requiredby the pressure vessel 104 and chassis 102 size and configuration. Inthe embodiment shown, each equilateral triangle side, or grid unit 712,is equal to 4.5″. Connections are typically made on chassis grid 700intersections, thus rod 310 lengths are all determined using the gridunit 712 and the resulting equilateral triangle chassis grid 700. Itwill be appreciated that in other embodiments of the chassis geometryconvention system the chassis grid 700 may comprise triangles other thanequilateral triangles, for example 90-45-45 triangles.

For the equilateral triangle and, the frame height 716 in thez-direction, or the nominal post 206 height between rail 200 axes, isequal to the grid unit 712. The frame width 718 in the x-direction, orthe nominal beam 204 length between rails 200, is equal to twice theheight of a single unit triangle, or 2*cos(30°)*grid unit=1.732*gridunit. In the embodiment shown, the chassis 102 is two grid units highand 1.732 grid units wide. The 2D rectangle formed by the x- and z-framemembers is defined as a single frame or cell. The exemplary chassis 102shown in FIG. 10 includes two frames in the z-direction and one frame inthe x-direction.

Pressure vessel 104 longitudinal centerlines are typically located atgrid 700 intersections or at triangle side midpoints. The first pressurevessel 702 and second pressure vessel 704 are located at the centralgrid intersection of the top and bottom frames, respectively. The linkstruts 500 coupling the first and second pressure vessel 702 704 to thechassis 102 are oriented along the grid 700 lines. As determined by thegrid geometry, the nominal distance from the centerline of the pressurevessel 104 to the connection of the link strut 500 to the chassis 102 isone grid unit 712. The actual length of the link strut 500 may becalculated based on a pressure vessel diameter 816, the grid unit 712and rail clamp 208 radius dimensions.

Pressure vessels 104 may also be placed externally to the grid frames,as illustrated by the third, fourth and fifth pressure vessels 706 708710. As with the first and second pressure vessel 702 704, the linkstruts 500 connecting the third, fourth and fifth pressure vessel 706708 710 to the chassis 102 align with the rails 200 whose axes lie ongridlines. As the third pressure vessel 706 is located on a verticalgridline that bisects the frame, the link strut 500 locations anddimensions are determined similarly to the link struts 500 for the firstand second pressure vessel 702 704, i.e. the centerline of the thirdpressure vessel 706 is located 0.5 grid units 712 above the top beam 204of the top frame.

The fourth and fifth pressure vessels 708 710 are located to the leftand the right of the top frame, respectively. The grid alignment in thex-direction results in the fourth and fifth pressure vessel 708 710location of 0.866 grid units 712 from the adjacent post 206 location.

One skilled in the art will appreciate that this additional link strut500 bracing creates very high stiffness in the chassis 102. In practicethe chassis 102 so braced is extremely resistant to deformation as aresults of the attachment of the pressure vessels 104 using the linkstruts 500.

Referring again to FIG. 7, the chassis grid 700 geometry as describedensures that pressure vessels 104, payloads, or other URV componentswill align and fit precisely with the rails 200 of any chassis 102 whichfollows the chassis geometry convention. This allows independent usersto develop modules that will interconnect with other researcher'schassis 102 and pressure vessels 104 in a standardized way, greatlyincreasing the number of usable components and modules available to theentire research community.

When the chassis 102 is built following the chassis grid 700 geometryand with adequate bracing, it may be rigid and dimensionally precise,even though made of flexible materials like 48″ long, 0.25″ diameterrods. Because the chassis materials are flexible, and because of thelarge capacity for correcting dimensional errors by tweaking link strut500 lengths away from nominal specified values, considerable libertiescan be taken with ‘forcing’ not-quite-aligned parts to fit withoutserious adverse effects to the chassis precision and alignment.

Using the above method to match the given pressure vessel 104 to a givenframe size, the overall chassis system is explicitly tolerant ofvariations in the pressure vessel diameter 816: the user is free tomaintain a standard diameter for housings or use different diameters(and a matching set of struts) for whatever reason the user sees fit.Typically this will arise when making mountings for commercialoff-the-shelf (COTS) products whose size is beyond the user's controle.g., mounting both a 1.4″ diameter camera housing and a 3.25″ sonarmodule on a 4.5″ frame with 3″ vessels. Using the formula above toderive the appropriate strut 500 lengths, attaching the pressure vessels104 with their differing diameters is trivial.

In some embodiments, it may be critical to the chassis geometryconvention that relative lengths of the posts 206, beams 204, and braces202 that define the chassis dimensions be such that the axes of therails 200 remain at the vertices of a 30-60-90 triangle, and it may becritical that the link strut 500 lengths be such that, for any wet ordry link 2200, the center to center distance from the axis of the linkstrut 500 to the rail 200 axis of the rail clamp 208 is equal to thecenter to center distance between the axes of any two rails 200 at theends of the post 206 (the frame height 716). In such embodiments, suchconfiguration ensures that all rods 310 and connection points lie on the60 degree triangular grid 700 and can attach to the rails 200 withoutdistortion or stress. Further, the actual grid unit 712 that drivesframe height 716 and link strut 500 axis to rail axis 200 radius iscompletely arbitrary, particularly so for the user building their ownsystem according to these guidelines but with no intent to interoperatewith other URVs 100 or use their pressure vessels 104. Whether the frameheight 716 is 4.5 inches (as in one example system) or any larger orsmaller number is user-defined as long as the 60-60-60 triangle geometryis maintained and the strut lengths keep the attachment points on grid.

One may manufacture pressure vessels 104 and/or components adhering topotentially several different grid sizes, especially ones that are evenmultiples of each other, for example 4.5″, 9.0″, 18″, and claim the gridsystem on whatever scale the user decides upon. The diameter of therails 200 also is arbitrary and set by user needs. In the exemplary 4.5″frame height 716 example system the rails 200 are ¼″ diameter. In a 9inch frame height 716, 1″ diameter rails 200 may be used for a muchheavier chassis 102, and the link strut 500 lengths and rail clamp 208dimensions reflect the required adjustments to the larger pressurevessel 104 and/or components. One may use rail 200 diameters that allowthe rails 200 to be hollow and use them as pressure vessels 104 forbatteries. One would simply shorten the link struts 500 and useappropriately sized rail clamps 208.

Adjustments to strut lengths will also correct when machined parts areout of tolerance—e.g., when a builder sent a rush job to a machinist andreceives wet links whose diameters are 2.900″ instead of 3.0″ and (beinga rush job) is required to use them anyway. In order for the chassis andhousing elements to align on a true 4.50″ triangular grid from theexample system, the length of the link struts need to be adjusted tomake up the 0.050″ radius difference.

Chassis rods 310 and link struts 500 are designed to a tolerance of+/−0.005″.

The last 0.55″+/−0.025″ of the link strut 500 is threaded typically with10-32 thread on 0.187″ diameter struts. A nominal depth to which thestrut should be threaded into its link is 0.50″ (assuming that thepressure vessel 104 diameter is exactly 3.0″). The link struts 500 cantherefore compensate for small misalignments due to out of spec pressurevessels 104 by simply adjusting how deeply they the link strut 500screwed into the pressure vessel 104. Since the rail clamp 208 should bealigned with the rail 200, the smallest available adjustment is onehalf-turn of the screw. The pitch of 10-32 screws is 0.03125″, so eachhalf turn of the 10-32 thread would make an adjustment of 0.015625.″

Since the radius of the example out-of-spec pressure vessel 104 is0.050″ less than the specified dimension, instead of screwing the linkstrut 500 the nominal 0.50″ into the pressure vessel 104, backing thelink strut 500 out by 1½ turns will lengthen the distance between thelongitudinal axis of the undersized pressure vessel 104 and the axis ofthe rail by 0.015625*3=0.046875″, leaving the tolerance only 0.003125″off.

In one exemplary form, nominally on a 4.5″ grid, with 0.25″ rails and3.0″ diameter pressure vessels, Link Struts are adjusted to extendexactly 2.875″ above the surface of the link to which they are attached,+/− any variation from 3.00″ in the link; e.g. if the housing measures2.90″ in diameter, 0.050″ of lost radius is added to each strut length

It will be appreciated that the 60-60-60 configuration is a preferredconfiguration for some embodiments but may be altered, whereappropriate, for alternative embodiments of the URVDS.

Using the chassis grid geometry convention, the frame width 718 isderived from the grid unit 712. In other embodiments, the frame width718 may be determined first and the grid unit 712 derived from the framewidth 718. Most notably, if the frame width 718 is required to matchexisting dimensional requirements such as when spacing deck-mountedpressure vessels 104 along a 2D surface with pre-drilled holes (whichmust be matched by the hole spacings of the URV 100), it may bedesirable to be able to express the chassis 102 dimensions as normalizedto the frame width 718. For example, for the frame width=unit length andthe frame height 716 is equal to the grid unit 712, the gridunit=tan(30°)*grid unit. This allows the user to adapt the frame width718 to pre-determined spacing requirements and derive new post 206, beam204 and brace 202 lengths.

Referring next to FIG. 8, an end view of a two-frame chassis pressurevessel 800 coupled to two differently-sized pressure vessels 104 isshown. Shown are a 3″ diameter pressure vessel 802, a 6″ diameterpressure vessel 804, the pressure vessel diameter 816, the pressurevessel radius 814, a 3″ pressure vessel link strut length 806, a 6″pressure vessel link strut length 808, beams 204, 3″ pressure vessellink struts 810, 6″ pressure vessel link struts 812, posts 206, andrails 200.

Using the chassis grid 700 as described in FIG. 7, lengths of linkstruts 500 for any size of pressure vessel 104 may be determined. Forthe 3″ outside diameter pressure vessel 802 shown in FIG. 8, the actuallink strut length 806 would be approximately 3.375 inches, taking intoaccount connection lengths and joint offsets.

On the chassis 102, since the frame dimensions and distances betweenrails 200 are fixed, and the diameter of any given pressure vessel 104or component to be attached may vary, a method is needed to adaptdifferently sized pressure vessels 104 to the chassis 102. Varying linkstrut 500 length is the primary method for adapting different pressurevessel diameters 816 to any given chassis 102. Modifying the length ofthe link strut 500 will accomplish this, and no other components orelements need be altered or adjusted to accommodate different sizes.

If a perimeter of the pressure vessel 104 does not extend past any beam204 (which would constrain its diameter), then in a single frame, asingle pressure vessel's radius 814 should not exceed the differencebetween the grid unit 712 and the adjacent rail 200 radius. For example,in a 4.5″ grid unit chassis with 0.25″ rails 200, a largest pressurevessel radius 814 possible is 4.375″, for the pressure vessel diameter816 of 8.75″. In practice there will be further circumstantialconstraints from the absolute maximum size such as interferences fromprotruding connectors and cables 1214, inaccessibility of screws, etc.

The size of the pressure vessel diameters 816 used is determined by theuser, but in practice, the pressure vessel diameter 816 about ⅔rds ofthe frame height 716, e.g., 3″ pressure vessels 104 on a 4.5″ highframe, is convenient in terms of clearances, finger space to reach in toattach and detach cables 1214, manipulate screws, etc.

Similarly to the 3″ diameter pressure vessel 802, the 6″ pressure vessellink strut length 808 is calculated using the grid dimensions. Theactual 6″ pressure vessel link strut length 808 is approximately 1.875″.It will be appreciated that the 6″ pressure vessel diameter 816 isgreater than the 4.5″ chassis cell height as shown, thus beams 204cannot be located at 6″ pressure vessel 804 locations.

If the pressure vessel 104 extends beyond any chassis beam 204, forcingthe pressure vessel 804 to clear the beam 204, then the pressurevessel's diameter 816 should not exceed the different between the gridunit 712 and the beam 204 diameter. In the 4.5″ grid unit chassis with0.1875″ diameter beams 204, the pressure vessel diameter 816 isconstrained to 4.3125″. Again, in practice there will be furthercircumstantial constraints from the absolute maximum size such asinterferences from protruding connectors and cables, inaccessibility ofscrews, etc.

Based on the grid layout as previously shown, the sum of the radii 814of vertically adjacent pressure vessels 104 may not exceed the grid unit712. For the exemplary 4.5″ grid unit 712, it can be seen that the 3″diameter pressure vessel 802 above the 6″ diameter pressure vessel 804are tangent to each other when mounted to the chassis 102 using the gridsystem.

For horizontally adjacent pressure vessels 104, the maximum sum of theradii 814 may not exceed √3*grid unit, i.e. for the 4.5″ grid unit 712,the sum of the radii 814 may not exceed 7.79″.

Referring next to FIG. 9, a perspective view of an exemplarynon-orthogonal heavy-duty chassis configuration 900 is shown. Shown arethe rails 200, the rail clamps 208, the beams 204, the posts 206 and thebraces 202.

As an example, shown in FIG. 9 is the exemplary heavy-duty chassis 900configured to carry a 1300 lb IMAX Underwater Camera system, used tocreate underwater movies in panoramic format for IMAX Theatres. The 63″diameter chassis 900 is built from the same four chassis memberelements: 1″ diameter rails 200, 9.0″ long posts 206, 15.6″ long beams204, and 18.0″ long braces 202. The chassis 900 uses the sameequilateral triangle chassis grid system described previously in FIG. 7,but with the grid unit 712 equal to 9.0″.

As stated, the chassis 900 in FIG. 9 includes frames that are notorthogonal to each other. The chassis system accommodates non-orthogonalconfigurations as well as the orthogonal configurations describedpreviously.

Referring next to FIG. 10, a perspective view of an exemplary IMAX®camera URV 1000 including the heavy-duty chassis of FIG. 9 is shown.Shown are the chassis 900, the pressure vessels 104, and the IMAX®camera 1002.

The pressure vessels 104 of the IMAX® camera URV 1000 include buoyancy,control and communication electronics, and thrusters providing 6-axismobility.

As previously described in FIG. 9, the exemplary large-scale, heavy-dutyURV 1000 including the heavy-duty chassis 900 is shown. The URVDS isconfigurable for both small-scale/light-duty and large-scale/heavy-dutyapplications.

Pressure Vessel System

The pressure vessel system comprises interconnected modules configuredto contain and support control electronics, batteries, sensors 4800,cameras, lights, thruster motors 5800 for locomotion, and similarcomponents necessary to the operation of the URV 100. Empty pressurevessels 104 may be also added to the URV 100 to provide additionalbuoyancy if needed. Each module includes a URVDS-specific standardmodule connection configuration such that all modules are configured atleast for attachment to other pressure vessel 104 modules, the externalchassis 102, and internal components.

Unless otherwise noted, all pressure vessel 104 modules may be comprisedof machined polycarbonate, acetyl (delrin), ABS or similar plastic, oraluminum, but may also be cast or manufactured by other means.

Referring next to FIG. 11, an exemplary pressure vessel in an empty anddry configuration is shown. Shown are the tube 1100, a first drynosecone 1102, a second dry nosecone 1104, a plurality of o-ring seals1106 and a plurality of tube mounting screws.

A pressure vessel shell (i.e. only the structural shell, withoutadditional components) is comprised of the tube 1100, interposed betweenthe first dry nosecone 1102 and the second dry nosecone 1104. The drynosecones 1102 1104 include an internal portion 1306 configured toslidably fit within an end of the tube 1100. Each dry nosecone 1102 1104also includes two o-ring seals 1106 located around the perimeter of theinternal portion 1306 of the dry nosecone and configured to provide awatertight seal between the tube 1100 and the dry nosecone, hence theterm “dry”, indicating that the module coupled to the tube 1100 providesa dry tube interior. Tube ends are coupled to the dry nosecones 11021104 by a plurality of tube mounting screws, using a standardized holeconnection configuration described further below.

Referring next to FIG. 12, an exemplary pressure vessel in a morecomplex configuration is shown. Shown are a first tube 1200, a secondtube 1202, a first wet nosecone 1204, a second wet nosecone 1206, acable manifold dry end cap 1208, a cable manifold link 1210, a dry endcap 1212, the tube mounting screws 1108, a plurality of internal cables2604 and an external cable 1214.

The pressure vessel 104 of FIG. 12 includes the first tube 1200 and thesecond tube 1202 interposed by the cable manifold link 1210. The cablemanifold link 1214 includes the internal portion 1306 on each endsimilar to the internal portion 1306 of the dry nosecones described inFIG. 11. The tube 1100 ends are coupled to the cable manifold link 1214similarly to the pressure vessel 104 of FIG. 11, utilizing the tubemounting screws 1108. The dry end cap 1212 is coupled to an end of thesecond tube 1202 distal to the cable manifold link 1210 with the samewatertight seal as described in FIG. 11, and the second wet nosecone1206 is coupled to the dry end cap 1212 with a non-watertight seal,hence the “wet” designation. The dry end cap 1212 may also be configuredto allow the external cable 1214 to exit the dry end cap 1212, asdescribed further below. The cable manifold dry end cap 1208 is coupledto an end of the first tube 1200 distal to the cable manifold link 1210,and the first wet nosecone 1204 is coupled to the cable manifold dry endcap 1208. As with the opposite end of the pressure vessel 104, the cablemanifold dry end cap 1208 provides a watertight seal between the cablemanifold dry end cap 1208 and the first tube 1200, and the first wetnosecone 1204 provides a non-watertight seal between the cable manifolddry end cap 1208 and the first wet nosecone 1204.

As shown in FIGS. 11 and 12, the two main elements of the pressurevessel 104 are the tubes 1100 and the modules configured to connect tothe tube 1100 or another module. The modules may include the nosecones2700 3200, end caps 3400 and cable manifold modules 1208 1210, as wellas other types and configurations of modules as described below, eachmodule configuration serving one or more other functions in another ofthe URVDS. Modules may be used to couple tubes 1100, terminate thepressure vessel 104 in a watertight seal, or connect to another moduleor peripheral module.

As will be appreciated by those skilled in the art, connections betweenthe tube 1100 and the various modules (e.g. a dry nosecone 2700, thecable manifold link 1210, the cable manifold dry end cap 1208 and thedry end cap 1212) are standardized so that most modules areinterchangeable, allowing a great degree of customization andreconfiguration of the pressure vessel 104.

Referring next to FIG. 13, the dry end cap 1212 including the standardmodule connection configuration is shown in one embodiment of theinvention. Shown are a plurality of tube mounting holes 1300, theplurality of link strut mounting holes 1302, two o-ring seals 1106, anda plurality of rim mounting holes 1304.

The standard module connection hole configuration is shown on the dryend cap 1212, but it will be understood by those of ordinary skill inthe art that the standard modules connection hole configuration istypically used for all modules in the URVDS, allowing modules to beinterchangeable without additional modification.

The dry end cap 1212 includes the generally cylindrical internal portion1306 and a generally cylindrical external portion 1308, wherein theinternal portion 1306 and the external portion 1308 are concentric, i.e.share a longitudinal axis 1310. A diameter of the external portion 1308is greater than a diameter of the internal portion 1306. In theembodiment shown in FIG. 13, the external portion 1308 includes acylindrical depression such that the external portion 1308 is generallytubular.

The dry end cap 1212 includes the tube mounting holes 1300 evenly spacedaround the internal portion 1306 of the dry end cap 1212 configured toslidably fit within the connecting tube 1100. The tube mounting holes1300 are located proximate to the external portion 1308 of the dry endcap 1212 (approximately 0.25″ from the external portion 1308 in theembodiment shown). A vertical plane is defined as a vertical plane thatbisects the dry end cap 1212, pressure vessel 104, tube 1100 or othermodule. A first tube mounting hole is vertical and also located on thevertical plane. The other 5 mounting holes are spaced evenly around theperimeter of the internal portion (or other module portion). The tubemounting holes 1300 are configured to receive tube mounting fastenersfor coupling the tube 1100 to the internal portion 1306 of the dry endcap 1212. In the present embodiment, the tube mounting holes 1300comprise six threaded holes configured to receive 6-32 size screws. Insome embodiments, the screw head may be configured to receive a magneticswitch sleeve 5300, as described further below. In another embodiment,the diameter of the tube mounting holes 1300 is configured to such thatsocket head screws fit slidably though, thus allowing the socket headscrews to be screwed flush to the end cap surface and thereby stillrestrain the tube 1100 against rotational movement but not risk crushingthe plastic tube 1100 wall.

Link strut mounting holes 1302 are provided on the perimeter of theexternal portion 1308 of the dry end cap 1212, i.e. a portion of the dryend cap 1212 not covered by the connecting tube 1100. In the presentembodiment, the link strut mounting holes 1302 include twelve radiallyoriented threaded holes (i.e. oriented similarly to the tube mountingholes) equally spaced around the tubular section, allowing the linkstruts 500 to be screwed into the dry end cap to couple the pressurevessel 104 to the chassis 102. In the present embodiment, the link strutmounting holes 1302 are configured to receive 10-32 screws, with theholes approximately 0.52″-0.55″ deep. In some module embodiments, thelink strut mounting holes 1302 may be threaded through-holes, where athrough-hole is defined as a hole passing through an object. Whiletypically only two or four link strut mounting holes 1302 on the dry endcap 1212 are utilized at one time for coupling to link struts 500,having 12 holes allows the attached pressure vessels 104 to be rotatedin 30 degree increments with respect to the chassis 102 or otherpressure vessels 104. This ability to rotate the pressure vessel 104 isuseful when the pressure vessel 104 contains components which aremounted at a particular angle or orientation, such as accelerometers,compasses, or cameras. In particular, lateral thrusters (as describedbelow) are usually mounted in pairs rotated 90 degrees with respect toeach other to provide maneuvering thrust both vertically andhorizontally. In the present embodiment, the link strut mounting holes1302 are 10-32 threaded holes.

Rim mounting holes 1304 are optionally included on the end of theexternal portion 1308. The rim mounting hole axes are parallel to theexternal portion longitudinal axis 1310. The rim mounting holes 1304 arelocated 1.0625″ from an external portion 1308 center. The rim mountingholes 1304 are six threaded holes equally spaced around the end of theexternal portion 1308, and configured to receive fasteners for couplingthe mounting rim 1900 to the dry end cap 1212 (as described furtherbelow). In the present embodiment, the rim mounting holes 1304 areconfigured to receive 6-32 size threaded fasteners and are approximately0.377-00.38″ deep. The rim mounting holes 1304 may be used to connectend caps or other modules back-to-back as is described further in themodule descriptions below. The top rim mounting holes are offset 15degrees counterclockwise from the tube mounting holes and the link strutholes.

A relationship between the tube mounting holes 1300 and the link strutmounting holes 1302 with respect to the perimeter of the dry end cap1212 is held constant for all modules so that the attached link struts500 may be attached in the same position on each end of the pressurevessel 104. The alignment of the tube mounting holes 1300 and the linkstrut mounting holes 1302 allows the link struts 500 or other elementsattached to the link strut mounting holes 1302 on each end of thepressure vessel 104 to be attached at the same angle relative to thepressure vessel 104.

Referring next to FIG. 14, an internal end of the dry end cap 1212 isshown. Shown are the internal portion 1306 of the dry end cap and aplurality of component mounting holes 1400.

Similarly to FIG. 13, the standard module connection hole configurationis shown on the dry end cap 1212, but it will be understood by those ofordinary skill in the art that the standard module connection holeconfiguration is typically used for all modules in the URVDS.

The end of the internal portion 1306 of the dry end cap 1212 configuredto fit within the tube 1100 includes the component mounting holes 1400configured to receive component mounting screws for coupling the dry endcap 1212 to internal components or mounting devices (as describedfurther below). The component mounting holes 1400 are oriented parallelto the longitudinal axis 1310 of the dry end cap 1212 and are evenlyspaced in a circular arrangement proximate to the perimeter of the endcap. The component mounting holes align with the locations of the linkstrut mounting holes and tube mounting holes, i.e. a top componentmounting hole is aligned with the vertical plane. In the embodimentshown, twelve threaded mounting holes are included. In the presentembodiment, the 12-hole configuration with a circular mounting holediameter of 2″ yields mounting hole spacings of 1.0″, 2.0″, 1.4142 (root2) and 1.732 (root 3)″. Having 12 mounting holes insures that internalcomponents that require a specific orientation such as an inclinometeror compass can be aligned from vertical to horizontal in 30 degreeincrements. The component mounting holes 1400 may be configured toreceive 4-40 size threaded fasteners, and are approximately 0.27-3″deep.

Referring next to FIG. 15, the pressure vessel tube 1100 is shown in oneembodiment of the present invention. Shown are the tube 1100 and theplurality of tube mounting holes 1300.

In the present embodiment, the tube 1100 includes an outside diameter of3 inches and an inside diameter of 2.5″. Those skilled in the art willappreciate that the diameter and thickness of the tube 1100 may be anydimension compatible with the module geometry.

Tubes 1100 include the radial pattern of six tube mounting holes 1300evenly spaced at 60 degree intervals at approximately 0.25″ from eachtube end, configured to match the tube mounting holes 1300 of thestandard module connection. The tube mounting holes 1300 allow the tube1100 to be screwed to the matching module mounting holes as shown inFIGS. 13 and 14.

While the screws hold the end cap onto the tube 1100 when not mounted onthe chassis 102, once the pressure vessel 104 is mounted onto thechassis 102, the link struts 500 securely hold the end caps and tube1100 together, and would do so even if all the mounting screws wereremoved, as the tube 1100 will be constrained between the fixed endcaps. Similarly, at depth (as with any submerged pressure vessel 104)hydrostatic pressure will always press the dry end cap 1212 module andthe tube 1100 together.

Tubes 1100 may be made of polycarbonate or acrylic plastic forlow-pressure duty in shallow water (200 feet), or aluminum, stainlesssteel, or other metals for deeper water duty at higher hydrostaticpressures. The current prototype system uses 3″ diameter acrylicpressure vessel tubes 1100 with ¼″ thick walls, which will support rateddepths of over 200 feet (100 psi). The URVDS supports both larger andsmaller diameter pressure vessels 104 as explained previously in thechassis system section.

All four of these commercially available materials share a common systemof sizing increments, with inside and outside diameters and wallthicknesses increasing in increments of 0.125″ across the typical rangeof diameters of the URVDS (typically 2.0″ to 6.0″ diameters, and 0.25 to0.5″ wall thicknesses). Thus for any tube 1100 made of one materialwithin that range of dimensions, tubes 1100 of the other materials willbe readily commercially available and interchangeable tubes can be madeand exchanged as the user requires, adjusting the wall thickness as thepressure rating for the new tube's diameter and material dictate.

As an example, the user might develop the URV 100 with low cost acrylictubes and then exchange them for aluminum tubes to withstand deeperoperating depths without having to re-design the URV 100. Similarly, ifa transparent housing is required the user might exchange the acrylictube for polycarbonate if the URV 100 is to be used in conditions ofshallower depth but where more impacts to the pressure vessel 104 mightoccur, since polycarbonate is more impact resistant than acrylic butless pressure resistant. Within the URVDS ranges of temperatures,coefficients of expansion of the tube materials are similar enough toallow them to be interchanged without special considerations. Othermaterials can be used; this is not an exhaustive list. For instance PVCpipe can also be used, subject to conditions detailed later; titanium orceramic tubes could be used for extreme depths.

Referring next to FIGS. 16 and 17, a reinforcement collar 1600 coupledto the tube 1100 is shown. Shown are the tube 1100, the reinforcementcollar 1600, the plurality of tube mounting holes 1300, a collar flange1700.

The reinforcement collar 1600 is generally tubular, including a flangeconfigured to slidably fit over the end of the tube 1100. Thereinforcement collar 1600 comprises aluminum or other material suitablefor greater resistance of torsional, tensile and bending loads thanpolycarbonate or acrylic. The end of the reinforcement collar 1600distal to the tube end is configured to match the geometry of the tubeend such that the reinforcement collar 1600 may couple with the modulesimilarly to the coupling of the tube end to the module. In the presentembodiment, the reinforcement collar flange 1700 is coupled to the tube1100 with marine epoxy glue, silicone sealant, or glue or sealantsuitable for watertight bonding to both the collar and the tube 1100 andincluding enough flexibility to accommodate different coefficients ofexpansion of the collar and the tube 1100. The reinforcement collar 1600includes tube mounting holes 1300 in the size, number and configurationas for the tube 1100. The reinforcement collar 1600 extent is configuredsuch that when the tube 1100 is coupled to the module using the tubemounting holes 1300, the tube 1100 portion contacts the o-ring seal 1106included in the link. As a result, the o-ring seal 1106 is notcompromised by any sealing flaws in the reinforcement collar 1600 gluejoint.

On an exemplary simple URV 100 when rails 200 are not used as asupporting structure but pressure vessels 104 are linked end to end, thesix screws that attach the tube 1100 to the module are the onlyfasteners. If the pressure vessel 104 is aluminum or stainless steelthis should present no problem. But if a plastic housing is desired(lowest cost, leaks are immediately detectable in a transparenthousing), tube mounting holes 1300 in the plastic pressure vessel tube1100 might be too fragile, and the strain on the screw holes may causethem to crack if excessive bending forces are present at the joint. Insuch cases, the aluminum reinforcement collar 1600 can be bonded to theacrylic tube 1100 end to reinforce the connection with the more robustscrew holes in aluminum supporting the tube 1100. The reinforcementcollar 1600 strengthens the tube 1100 mounting holes 1300 when the tubemounting screws are the only fasteners on the long, jointed pressurevessel 104 without the supporting chassis 102.

Referring next to FIG. 18, a perspective view of the external end of thedry end cap 1212 is shown. Shown are the internal portion 1306, theexternal portion 1308, two o-rings, two o-ring grooves 1800, theplurality of tube mounting holes 1300, the plurality of link strutmounting holes 1302, a shoulder 1802, a plurality of strain reliefgrooves 1804, and the plurality of rim mounting holes 1304.

The dry end cap 1212 is comprised of the internal portion 1306 integralwith the concentric external portion 1308, where an external portion1308 diameter is greater than an internal portion 1306 diameter. In theembodiment shown, the external portion 1308 diameter is approximatelyequal to the tube outside diameter, and the internal portion 1306diameter is approximately equal to the tube inside diameter. A free endof the internal portion 1306 is a first end 1806 of the dry end cap1212, and a free end of the external portion 1308 is a second end 1808of the dry end cap 1212. In some embodiments, the external portion 1308,the internal portion 1306, or both, may include a cylindrical void suchthat the portion is tubular. In the embodiment shown in FIG. 18, theexternal portion 1308 includes the external void and is tubular. In someembodiments an internal and an external void will not connect, but inother embodiments the internal portion 1306 may contain a through-voidor voids for passing cables 1214 or other elements longitudinallythrough the dry end cap 1212, in which case an additional waterproofseal would be provided. The external void also allows for clearance ofunderwater connector and cables 1214 within the external portion 1308.The internal portion 1306 is configured to slidably fit within the tube1100 of the pressure vessel 104. The internal portion 1306 includes thestandard tube mounting holes 1300 located proximate to the externalportion 1308, as described above. The internal portion 1306 alsoincludes the two circular o-ring grooves 1800 around an outer perimeterof the internal portion 1306 proximate to the first end 1806 forreceiving, each o-ring groove 1800 configure for receiving the o-ringseal 1106. The o-ring seal 1106 is a rubber seal or other o-ring typeseal suitable for sealing between the tube 1100 and the dry end cap1212, and is present in all modules requiring a watertight seal betweenthe module and the tube 1100. The height of the o-rings in the o-ringgrooves 1800 are configured to compress and form a watertight seal whenthe internal portion 1306 is inserted into the tube 1100, forming thewatertight seal between the floating pressure wall and the tube 1100.

The intersection between the internal portion 1306 and the externalportion 1308 forms the shoulder 1802 for receiving the end of the tube1100 and is configured such that the perimeter of the tube 1100generally aligns with the perimeter of the external portion 1308. Theexternal portion 1308 also may include at least one approximatelysemicircular strain relief groove 1804 in the second end 1808 of the dryend cap 1212. The strain relief groove 1804 is configured to allow theelectrical cable 1214 to pass through the external portion 1308 whenanother module or component is mounted to the second end 1808. In theexemplary dry end cap 1212 shown in FIG. 18, the dry end cap 1212includes six strain relief grooves 1804 equally spaced with respect tothe perimeter of the dry end cap 1212. In an embodiment that includesrim mounting holes 1304, the strain relief grooves 1804 are locatedbetween rim mounting holes 1304. A top strain relief groove and a bottomstrain relief groove are oriented vertically. The other 4 strain reliefgrooves 1804 are radially arrayed such that all strain relief grooves1804 are evenly spaced. The strain relief grooves are 0.25″ deep and0.25″ wide, where a base of the strain relief groove 1804 forms aD-shape. In other embodiments, if cable 1214 pass-through is not arequirement, the strain relief grooves 1804 may be eliminated from theexternal portion 1308. As previously described, as with all modules thedry end cap 1212 includes in the standard configuration the tubemounting holes 1300, component mounting holes 1400, and may optionallyinclude rim mounting holes 1304.

Referring again to FIG. 18, the dry end cap 1212 typically provides awatertight seal for the end of the tube 1100, provides a connectionpoint for the link struts 500 to couple to the chassis 102, and alsoprovides connection points for connecting additional components to theexternal end of the pressure vessel 104 (i.e. the portion opposite tothe tube 1100 end). The dry end cap 1212 may be configured to provideonly a seal, or may be used with voids and notches for one or morecables to allow the interior cable 2604 to exit the pressure vessel 104.The dry end cap 1212 may also be used to connect two tubes 1100end-to-end, when the mounting rim 1900 is coupled to the dry end cap1212 as shown further below.

Referring next to FIG. 19, an exploded cross-sectional view of oneembodiment of the dry end cap 1212 with the mounting rim 1900 is shown.Shown are the mounting rim 1900, a plurality of mounting rim screws1902, the plurality of tube mounting holes 1300, a cable gland 1906, andthe cable 1214.

The mounting rim 1900 is tubular in shape and configured toconcentrically couple to the external end of the dry end cap 1212 orother end module configured for the standard end connection. A mountingrim 1900 outer diameter is equal to the dry end cap internal portion1306 outer diameter, thus forming a shoulder. A mounting rim 1900 innerdiameter approximately aligns with the inner diameter of the cylindricalvoid in the tubular external portion 1308 of the dry end cap 1212. Themounting rim 1900 includes rim mounting holes 1304 in the sameconfiguration as the rim mounting holes 1304 of the standard connectionconfiguration. The mounting rim 1900 also includes the plurality of tubemounting holes 1300 through the wall of the mounting rim 1900,configured to couple to an end cap collar 2000 shown in FIG. 20 or othercomponent or module. The mounting rim 1900 is coupled to the end of theexternal portion 1308 using the mounting rim screws 1902.

The dry end cap external portion 1308 may be solid, as shown in FIG. 18,or may include at least one void/hole parallel to the longitudinal axisof the external portion 1308 configured to receive the cable 1214 andthe cable gland 1906. The cable gland 1906 is coupled to an externalportion of the void and provides a waterproof seal for the cable 1214. Aportion or all of the void may be threaded. Also shown is the cable 1214being received by the strain relief groove 1804 in the dry end cap 1212and thus exiting the pressure vessel 104. After the cable 1214 is placedin the strain relief groove 1804, the mounting rim 1900 is screwed on,securing the cable 1214 in place.

The mounting rim 1900 may also be used in assembly to couple two modulestogether, for example, as shown below in FIG. 20, or to couple the tube1100 to the dry end cap 1212 or other end cap module 3400 including rimmounting holes 1304.

Referring next to FIG. 20, the end cap collar 2000 in one embodiment ofthe present invention is shown. Shown are the plurality of tube mountingholes 1300, the plurality of mounting rim holes, and an end cap collarshoulder 2002.

The end cap collar 2000 is tubular with an interior shoulder 2002 (i.e.an outside diameter of the end cap collar 2000 is constant, while aninterior thickness varies) and includes the standard tube mounting holes1300 and rim mounting hole 1304 configurations. The radial tube mountingholes 1300 are located through a thinner wall portion of the end capcollar 2000. The thinner wall portion is configured to internallyreceive the mounting rim 1900. The longitudinal rim mounting holes 1300are located in the inner shoulder 2002 area. The end cap collar 2000 iscoupled to the end of the external portion 1308 of the dry end cap 1212(or other similarly configured module) using axial screws, with thethicker portion of the end cap collar 2000 abutting the dry end cap1212. An outer perimeter of the end cap collar 2000 generally alignswith the perimeter of the external portion 1308 (i.e. also aligning withthe tube 1100 outside diameter) when the end cap collar 2000 is coupledto the dry end cap 1212.

The end cap collar 2000 and mounting rim 1900 may be used to connect twomodules end-to-end, as illustrated below.

Referring next to FIG. 21, a cross-sectional view of a first dry end cap2100 and a second dry end cap 2102 are shown coupled together via themounting rim 1900 and the end cap collar 2000. Also shown are a firstcable 2104, a first cable gland 2106, a second cable 2108, a tubemounting screw 2112 and a second cable gland 2110.

As previously described, the first dry end cap 2100 is coupled to themounting rim 1900 with the mounting rim screws 1902, securing the cable1214 in the strain relief groove 1804 and providing an exterior shoulderat the wet end of the first dry end cap 2100. The second dry end cap2102 is coupled to the end cap collar 2000 such that the shoulder of theend cap collar 2000 faces outward from the second dry end cap 2102,securing the cable 1214 in the strain relief groove 1804 and providingan interior shoulder. The mounting rim 1900 and end collar diameters arechosen such that when mounting to the dry end caps 2100 2102 or othercompatible modules, the mounting rim 1900 fits slidingly within theouter portion of the end cap collar 2000 since the mounting rim 1900outside diameter and the end cap collar 2000 inside diameter are thesame as the inside diameter of the tube 1100. The mounting rim 1900 isthen coupled to the end cap collar 2000 using the radial tube mountingholes 1300 in each element and compatible fasteners.

Two pressure vessels 104 that normally would be mechanically joined withthe continuous dry link 2200 module or the cable manifold link module1210 sometimes need to be separated into two independently sealedpressure vessels 104. For example, a sensor payload or battery packmight be frequently disconnected without compromising their seals eachtime as would happen with the dry link 2200 or the cable manifold link1210. In those instances the mounting rim 1900 and the end cap collar2000 may be used to couple two dry end caps 1212 back-to-back. The endcap collar 2000 and the mounting rim 1900 may also be used to connecttwo lateral thruster modules back to back, as discussed below in thethruster section.

Referring next to FIG. 22, a perspective view of the dry link 2200module is shown. Shown are a first internal portion 2202, a secondinternal portion 2204, the external portion 1308, the link strutmounting holes 1302, the tube mounting holes 1300, and the componentmounting holes 1400.

The exterior of the dry link 2200 is configured similarly to the dry endcap 1212, with the addition of the additional internal portion 2204 onthe second end 1808 of the external portion 1308. The dry link 2200comprises the first internal portion 2202 and the second internalportion 2204 interposed by the external portion 1308, forming a shoulderon each side of the external portion 1308. The internal portions 22022204 are configured similarly to the internal portion 1306 of the dryend cap 1212. As with the dry end cap 1212, the shoulder is configuredsuch that the tube 1100 may slidably fit over each internal portion 22022204 of the link and abut the shoulder. The interior cavity of the drylink 2200 in one embodiment is a continuous bore to allow for internalcables 2604 to pass through unhindered between portions of the pressurevessel 104 separated by one or more modules. The external portion 1308includes the radial link strut mounting holes 1302 in the standardconfiguration. The link strut mounting holes 1302 are blind holes, i.e.do not penetrate into the interior cavity of the dry link 2200 in orderto preserve the watertightness of the interior of the pressure vessel104.

The internal portions 2202 2204 of the dry link 2200 on each side of theexternal portion 1308 are configured similarly to the dry end cap 1212,including two o-ring seals 1106 around the perimeter at each end and thetube mounting holes 1300 and component mounting holes 1400 in each endof the dry link 2200. The tube 1100 and the links struts are fastened tothe dry link 2200 similarly as to the dry end cap 1212, as previouslydescribed.

Referring again to FIG. 22, the dry link 2200 allows the mechanicalintegration of two pressure vessels 104 while preserving a high degreeof the modularity. The dry link 2200 mechanically connects two pressurevessels 104, each of which is only sealed at one end, with the o-ringsealed watertight passage between them to form the single largerpressure vessel 104. The dry link 2200 is useful when a large number ofinternal wires or cables 2604 need to pass between the two separatesections but the single very long pressure vessel 104 would beimpractical or if the pressure vessels 104 have logically differentfunctions and are best managed as separate modular units or need to beoccasionally separated (e.g., a sensor housing 4802 or a battery housingthat might need to be exchanged regularly).

Referring next to FIG. 23, a perspective view of the cable manifold link1210 is shown in one embodiment of the present invention. Shown are thecentral external portion 1308, a plurality of ports 2300, the pluralityof tube mounting holes 1300, the plurality of link strut mounting holes1302, a plurality of port inserts 2302, and the plurality of componentmounting holes 1400.

The cable manifold link 1210 is similar in configuration to the dry link2200, with the exception of the central external portion 1308. Thecentral external portion 1308 of the cable manifold link 1210 is widerto accommodate a plurality of underwater electrical connection portsarrayed on the perimeter of central external portion 1308 of the cablemanifold link 1210. In the version shown in FIG. 23, the cable manifoldlink 1210 includes two rows of eight ports evenly spaced around theexternal portion 1308 perimeter, and the row of link strut mountingholes 1302 in the standard configuration. Those skilled in the art willnote that other numbers and configurations of ports are possible. Aswith the dry link 2200, the interior cavity of the cable manifold link1210 is a continuous bore to allow internal cables 2604 and othercomponents to pass through the cable manifold link 1210.

The ports comprise a plurality of port holes 2400, configured match thespecifications of the port insert 2302 manufacturer (threaded being themost widely used), penetrating the link, as shown below in FIG. 24. Theport holes 2400 are configured to receive the port insert 2302configured to provide a watertight seal at the port 2300 location. Inthe embodiment shown in FIG. 23, the port insert 2302 comprises anelectrical connector, e.g. those produced by Ikelite, Fischer, SeaConand Impulse. In the exemplary link of FIG. 23, port holes 2400configured for receiving Ikelite connectors are shown, although it willbe appreciated that port holes 2400 in the same link may be configuredfor different types of connectors. In other embodiments the ports maycomprise watertight cable glands from HexSeal and other companies. Theport holes 2400 may be threaded as required to match the port insert2302, typically M1×12 or ½″-20 threads. Custom manifolds can be madethat handle more than one company's connectors, e.g., four Fischerconnectors with M1×12 metric threads, and eight Ikelite connectors with½″-20 UNRF threads, etc. This is useful when existing equipment withdifferent plugs have to be mated to the single pressure vessel 104.

Examples of port inserts 2302 that may be used with the cable manifoldports 2300 include an Ikelite cable gland rated to 300 ft. depth, anIkelite 5-wire socket and 5-wire plug rated to a 300 ft. depth, aFischer 11-wire socket and plug rated to a 300 ft. depth, and a TeledyneImpulse 6 wire socket and plug rated to 20,000 ft. depth.

The cable manifold link 1210 may be used when a large number ofelectrical connections need to fan out from the single pressure vessel104 to several additional pressure vessels 104. Like the dry link 2200,the cable manifold link 1210 incorporates two O-ring seals 1106 on eachend to connect two pressure vessels 104 together and the continuouscavity which allows direct electrical wiring between the two sections.The cable manifold link 1210 also includes the standard connectionconfiguration. The cable manifold link 1210 also includes four, eight,or sixteen threaded mounting port holes 2400 for commercially availablewaterproof electrical connectors. One pressure vessel 104 can thus haveup to 16 easily maintained electrical cables 1214 passing from it toother vessels which can be disconnected at will. For example, thepressure vessel 104 containing a main computer could include variouselectrical connections terminating at the ports 2300, for example: onecable port 2300 to couple to the cable 1214 configured to pass commandsand data to the user at the surface, six cable ports 2300 configured toconnect to cables 1214 going to various sensors 4800 in other pressurevessels 104 and six cable ports 2300 configured to connect to cables1214 extending to motor controllers in each of six thruster pressurevessels 106. If additional connections are required, more cable manifoldlinks 1210 are easily added, or a custom cable manifold with therequired number of connections is easily built.

The cable manifold link 1210 also allows underwater implementation ofstandard star-topology networks like UTP Ethernet or USB in connectionsbetween pressure vessels 104, as shown further below in the electricaldistribution section.

Referring next to FIG. 24, a perspective view of the cable manifold link1210 showing the interior of the cable manifold link 1210 is shown.Shown are the port holes 2400, the ports 2300, a plurality of port caps2402, and the port inserts 2302.

As previously described in FIG. 23, the cable manifold link 1210includes the plurality of threaded port holes 2400 arrayed around theperimeter of the external portion 1308, configured to receive the portinsert 2302 for connecting to the cable 1214 or other connection means.Also shown are the plurality of port caps 2402. The port caps 2402include a threaded cylinder to fit the port 2300 and a top flangeconfigured for unscrewing or alternate removal means from the port hole,and are typically provided by the manufacturer of the electricalconnector. The port cap 2402 also includes an o-ring or other means toprovide the watertight connection between the port cap 2402 and thecable manifold link 1210. The port hole may be recessed below the outerperimeter of the cable manifold link 1210 external portion 1308 to forma flat o-ring mating surface.

The port caps 2402 are plugs to seal the port holes 2400 when fewerports 2300 are needed than the number of port holes 2400 provided. Theport cap 2402 is typically available from the port insert 2302manufacturer an attach to the port hole 2400 with the same watertightattachment.

Referring next to FIG. 25, a cross-section of the cable manifold dry endcap 1208 is shown. Shown are the ports, the port inserts 2302, the linkstrut mounting holes 1302, the component mounting holes 1400, theo-rings, and the tube mounting holes 1300.

In a variation of the dry end cap 1212, the external portion 1308 of thedry end cap 1212 may include the plurality of threaded port holes 2400configured to receive the port insert 2302 for connecting to the cable1214 or other connection means. The cable manifold dry end cap 1208includes the internal cavity extending into the external portion 1308 toallow the port holes 2400 to connect to the internal cavity. Theplurality of link strut mounting holes 1302 are also included in theexternal portion 1308. The embodiment shown in FIG. 25 terminates in aflat portion at the sealed end, and does not include the rim mountingholes 1304, but in other embodiments may include rim mounting holes 1304and other end configurations of the dry end cap 1212.

Referring next to FIG. 26, a perspective view of a central pressurevessel 2600 including the cable manifold link 1210 with attachedauxiliary pressure vessel 2602 is shown. Shown are the central pressurevessel 2600, the plurality of auxiliary pressure vessel 2602, the cablemanifold link 1210, the plurality of internal cables 2604, a pluralityof external cables 1214, and the plurality of ports.

Components of the auxiliary pressure vessel 2602 are coupled to externalcables 1214 fitted with mating connectors for electrical and/orcommunicative coupling with the matching port insert 2302 of the cablemanifold link 1210. The port insert 2302 is coupled to the internalcable 2604 and thus to a component or components residing in the centralpressure vessel 2600. The arrangement shown in FIG. 26 is a radialarrangement, but those of ordinary skill in the art will note that manyother types of arrangements are possible, for example serialarrangements or a combination of both.

The radial configuration of the connecting ports on the cable manifoldlink 1210 allows for many different attachment points and configurationsof peripheral equipment. Shown here is the cable manifold link 1210electrically coupled to five peripheral pressure vessels 104. The cables1214 2604, port inserts 2302 and mating connectors may be configured toaccommodate star-topology wiring schemes such as UTP Ethernet switches,Power-over-Ethernet, fiber optic Ethernet, USB hubs, and RS232multiplexers.

Referring next to FIG. 27, the dry nosecone 2700 in one embodiment ofthe present invention is shown. Shown are the tubular internal portion1306, a parabolic external portion 2702, the two o-rings, the pluralityof component mounting holes 1400, the plurality of link strut mountingholes 1302, the plurality of tube mounting holes 1300, and the shoulder.

The internal portion 1306 of the dry nose cone is configured similarlyto the internal portion 1306 of the dry end cap 1212, including theo-rings, component mounting holes 1400 and tube mounting holes 1300 inthe standard configuration. The dry nosecone 2700 also includes thesolid parabolic external portion 2702, which is integral to the internalportion 1306. The base of the parabolic external portion 2702 abuts theinternal portion 1306, forming the shoulder for receiving the tube 1100,as previously shown with the dry end cap 1212. The end of the parabolicportion distal to the tube 1100 forms the tapered, streamlined parabolicnosecone.

The dry nosecone 2700 is similar to the dry end cap 1212, sealing theend of the pressure vessel 104 but also providing a low drag profile. Anexemplary use of the dry nosecone 2700 is to lessen hydrodynamic dragalong the URV's 100 main axis of travel, particularly on the URV 100with a finite on-board power supply, as in FIG. 74. The dry nosecone2700 comprises, ABS plastic, Delrin, acrylic, aluminum or other suitablematerial. Use of dry nosecones 2700 for buoyancy modules 108 isdiscussed further below in the buoyancy section.

Referring next to FIG. 28, a perspective view of a floating pressurevessel wall 2800 is shown. Shown are the o-ring seals 1106, the o-ringgrooves 1800, and the component mounting holes 1400.

The floating pressure vessel wall 2800 comprises a generally solidcylinder configured to snugly fit within the tube 1100 forming a sealusing the o-ring seals 1106, with the central axis of the floatingpressure vessel wall 2800 aligned with the longitudinal axis of the tube1100. In the example prototype system, the floating pressure vessel wall2800 includes an outside diameter of 2.49″ to fit inside the 2.50″inside diameter tube 1100. The height of the o-rings in the o-ringgrooves 1800 will be greater than 0.01 inches, forming the watertightseal between the floating pressure vessel wall 2800 and the tube 1100.

Unlike the previously described modules, the floating pressure vesselwall 2800 is not configured to abut the end of the tube 1100, butinstead is placed at a desired location inside the tube 1100 by anotherinterior support, for example by the floating pressure vessel wall 2800support column 2900, as described below. The floating pressure vesselwall 2800 can be positioned anywhere along the inside of the tube 1100.The floating pressure vessel wall 2800 includes the two o-ring grooves1800 and two o-ring seals 1106 as previously described. Like otherpressure vessel 104 modules, the floating pressure vessel wall 2800includes the standard component mounting hole 1400 configuration. Thecomponent mounting holes 1400 are blind holes to maintain the waterproofseal. The floating pressure vessel wall 2800 may also include one or twoaxially-oriented through-holes for mounting sealed underwater connectorsfor routing the waterproof cable 1214 and the cable gland through thefloating pressure vessel wall 2800. The through-hole may be threaded tomatch the thread of the connector, or the connector may be secured witha nut or other means.

The floating pressure vessel wall 2800 may comprise acrylic,polycarbonate, ABS, or another engineering plastic for shallower depths,but may be anodized aluminum, stainless steel, titanium, or ceramic(with matching tube material) to achieve greater depths.

Sealing the pressure vessel 104 with end caps that abut the ends of thepressure vessel tube 1100 is simple and effective, but the tube 1100 isexposed not only to the radial hydrostatic water pressure around thetube 1100, but to the axial water pressure pressing the end caps in aswell. At a depth of 200 feet, the approx. 100 psi acting on the 4.9 sqinch area of the 2.5″ diameter tube 1100 yields 490 lbs of purely axialload on the end caps, which the rims of the end caps transfer to thetube's 1100 2.16 sq inch cross section, for 227 additional psi of axialpressure. Relieving that pressure would allow the pressure vessel 104 towithstand more radial pressure and allow deeper depth.

A second concern with pressure vessels 104 sealed with end caps is thatit is sometimes useful to have the dry pressure vessel 104 length beless than the length of the tube 1100 mounted on the chassis 102, sothat the single pressure vessel tube 1100 can contain a dry space forelectronics connected through the floating pressure vessel wall 2800 toinstruments in an adjacent large freely flooded space within the tube1100. As an example, delicate instruments such as pressure sensors,thermometers, or conductivity sensors might need to extend outside thepressure vessel 104, but be within the tube 1100 in a space flooded withwater but protected from impacts or debris. Having the floating pressurevessel wall 2800 that can be in the middle of the tube 1100 providesthis capability.

Another race where it would be useful to separate the pressure wall fromone of the pressure vessel 104 end caps would be when an unusually largeor long connector is used on one end, or if the cable 1214 connected tothe connector is unable to bend in a tight enough radius to be fit inthe small space between the connector and the strain relief groove 1804in the dry end cap 1212. In such a case it would be useful to move theconnection to which the connector is attached far enough away from theend of the tube 1100 to allow sufficient clearance. The floatingpressure vessel wall 2800 will accomplish this.

The floating pressure vessel wall 2800 also supports pressurecompensated housings as an alternate method of preventing water ingress.If the contents of the pressure vessel 104 are impervious to oil and tothe pressure at the depth of operation (for example, if all capacitorson a circuit board are ceramic and there are no electrolytic capacitorsthat leak under high pressure) filling the interior volume with oilrelieves both axial and radial pressure and renders the pressure vessel104 incompressible and capable of deep descents if all pressure vessels104 in the URV 100 were similarly treated. The pressure vessel 104 isthen no longer a “pressure” vessel but simply a housing that preventsintrusion of damaging seawater past the o-ring seals 1106.

Referring next to FIG. 29, a perspective view of a floating pressurevessel wall support column 2900 in one embodiment of the presentinvention is shown. Shown are a first support column ring 2904, a secondsupport column ring 2904, a plurality of support column rails 2906, aplurality of support column fasteners 2908, and the plurality ofcomponent mounting holes 1400.

The support column 2900 is comprised of the first support column ring2904 and the second support column ring 2904 interposed by at leastthree support column rails 2906, thus forming a cylinder shape withmostly open sides. While three support column rails 2906, as shown inFIG. 29, are normally sufficient to insure mechanical stability, incases where extreme pressure or other mechanical stress might beexpected to apply loads onto the floating pressure vessel wall 2800, 4or 6 support column rails 2906 can be used to distribute the load.

The support column rings 2902 2904 are toroidal in shape and orientedsuch that the first support column ring 2904 center and the secondsupport column ring 2904 center align. Each support column ring 29022904 includes component mounting holes 1400 in the standardconfiguration. The component mounting holes 1400 receive the supportcolumn fastener 2908 that couples the support column rail 2906 to thering, the support column rail 2906 being configured to receive thethreaded fastener 2908. In some embodiments the component mounting holes1400 may be countersunk so that support column fasteners 2908 that areflat-headed can be flush with an outer surface of the ring 2902 2904such that the ring 2901 2904 rests flat against the floating pressurevessel wall 2800. The support column rails 2906 can be round 4-40internally threaded standoffs 3702 custom made to length or made ofmultiple commercially available 4-40 threaded standoffs 3702 coupledtogether in series. Commercially available standoffs 3702 may becombined freely with custom standoffs 3702 to make support column rails2906 of any required length. For example to adjust the lengths of 12″long support column rails 2906 to 12.75″, standard 0.25″ diameterstandoffs 3702 could simply be added to support column rail 2906 endswithout affecting performance. The standoffs 3702 may be either round orthe common hexagonal type, but round standoffs 3702 will allowattachment of circuit board mounting clips 4200 and thus afford moreoptions for mounting circuit boards as described later. In otherembodiments, the standoffs 3702 may be male/female threaded.

In other embodiments, multiple sets of support column rings 2902 2904and support column rails 2906 may be used, e.g. three support columnrings 2902 2904 separated by two sets of support column rails 2904. Inyet another embodiment, the support column 2900 may be fastened to anend cap in lieu of fastening to the support column ring 2902 2904. Inthat case, the standoffs 3702 would need to be threaded male on one endand female on the other to thread into the end cap and be secured byscrews at the Mounting Plate end. Note that this type of support column2900 cannot be formed between two link modules or end cap modules 3400as there would be no way to either get the assembly inside the pressurevessel 104 once assembled, or to assemble it inside the pressure vessel104.

Referring next to FIG. 30, a portion of the pressure vessel 104including two floating pressure vessel walls 2800 and the support column2900 is shown. Shown are the tube 1100, a first floating pressure vesselwall 3000, a second floating pressure vessel wall 3002, the supportcolumn 2900, and the cable 1214.

The support column 2900 in one embodiment is used interposed between thefirst floating pressure vessel wall 3000 and the second floatingpressure vessel wall 3002, bracing the floating pressure vessel walls3000 3002 against water pressure to define the interior volume of thepressure vessel 104. This is useful in cases where the user does notwish to use two dry end caps 1212 to seal the pressure vessel 104. Useof the support column 2900 also affords several circuit board mountingoptions discussed later.

Since the floating pressure vessel wall 2800 is not fastened to the tube1100 or the end cap, using the floating pressure vessel wall 2800 toseal the pressure vessel 104 typically requires some means of preventingaxial water pressure from forcing the floating pressure vessel wall 2800inward and collapsing the interior volume until the air pressure withinequals the water pressure without. The support column 2900 should becapable of withstanding at least the pressure at the required operatingdepth: for example, 2.5″ diameter floating pressure vessel walls 2800have a surface area of approximately 4.9 sq. in.×0.445 psi/foot,yielding 490 lbs pressing inward at 200 feet.

Another example of use of the support column 2900 would be when the userdesires to avoid having the axial load of water pressure supported bythe pressure vessel tube 1100, as is the case when the simplestarrangement of the tube 1100 with two dry end caps 1212 is used. Withthe floating pressure vessel wall 2800, the axial load is borne by thesupport column rails 2906 rather than the tube 1100, reducing thepossibility of the axial water pressure causing buckling of the tube1100.

Use of at least one floating pressure vessel wall 2800 is advised whenoperation near maximum depth is anticipated. If the URV 100 is operatedat depths where the axial hydrostatic pressure and excessive length ofthe support column rails 2906 in the long pressure vessel 104 makebuckling of the support column rails 2906 a concern, additional supportcolumn rings 2902 2904 can be added to control the buckling by reducingthe length-to-cross-section ratio of the support column rails 2906.

Referring next to FIG. 31, a wet link 3100 in one embodiment of thepresent invention is shown. Shown are the strain relief grooves 1804,the link strut mounting holes 1302, the tube mounting holes 1300, themounting rim 1900, the mounting rim screws 1902 and the rim mountingholes 1304.

The wet link 3100 is tubular, with a generally constant inner diameter.A wet link 3100 outer diameter steps inward proximate to an endreceiving the tube 1100, forming the shoulder for receiving the tube1100. The tube 1100 end also includes the standard tube mounting holes1300. The wet link 3100 end distal to the tube end includes the strainrelief grooves 1804 as shown in FIG. 18. The wet link 3100 also includesthe rim mounting holes 1304 and the link strut mounting holes 1302 onthe wet end cap end distal to the tube end. The mounting rim 1900 asshown in FIG. 19 is typically coupled to the rim mounting holes 1304.

The holes and dimensions of the wet link 3100 also conform to thestandard geometry and spacing for the link modules to facilitateinterchangeability and recombinability.

Referring again to FIG. 31, the wet link 3100 may provide afree-flooding end to the pressure vessel 104, may mechanically connecttwo separate, fully enclosed pressure vessels 104 end to end and alsoprovide attachment points for the link struts 500 that connect thepressure vessel 104 to the chassis 102. The wet link 3100 provides nosealing. The space between connected pressure vessels 104 is freelyflooded with water (hence the term ‘wet’). In one form, connectingpressure vessels 104 are sealed with floating pressure vessel walls 2800where they join the wet link 3100, and any electrical connectionsbetween the connected pressure vessels 104 or to other pressure vessels104 may be done through separate waterproof cables 1214 and connectorsattached to the floating pressure vessel walls 2800. The cables arecaptured in one of the strain relief grooves 1804 when the wet end capis coupled to the mounting rim 1900.

The wet link 3100 provides various functions: constraining the floatingpressure vessel walls 2800 and support column; capturing and providingstrain relief for the cable 1214 that penetrates the floating pressurevessel wall 2800, provide mounting points for the link struts 500.Additionally, the twelve rim mounting holes 1304 allow the mounting rim1900 to be rotated in 30 degree increments, allowing modules in thesingle pressure vessel 104 to be rotated in 30 degree increments withrespect to the chassis 102 and other pressure vessels 104. As anexample, this allows lateral propeller 6302 modules to be mountedorthogonally from each other to provide both vertical and lateralthrust,

Referring next to FIG. 32, a wet nosecone 3200 in one embodiment of thepresent invention is shown. Shown are the tube mounting holes 1300 and aplurality of flooding holes 3202.

The wet nosecone 3200 comprises a hollow parabolic cone shape with anosecone base configured to slidably fit over the wet link 3100 (i.e.with a same outside diameter and inside diameter as the tube 1100 andincluding the tube mounting holes 1300), mounting rim 1900, or othermodule configured to receive the wet nosecone 3200. The wet nosecone3200 is coupled to the receiving module using the tube mounting holes1300 and associated fasteners. The wet nosecone 3200 also includes theplurality of flooding holes 3202 spaced over the nose portion of the wetnosecone 3200 and configured to allow water to easily flood thenosecone. In the present embodiment, the nosecone 3200 includes 8 holesapproximately ⅜″ in diameter, but any suitable number of holes may beused.

When the pressure vessel 104 is terminated with the wet end cap or thedry end cap 1212 with mounting rim 1900, the free flooding wet nosecone3200 may be attached to the end cap for hydrodynamic streamlining or toprotect the sensor 4800 that may be exposed to water. Although the lackof o-rings would itself cause the nosecone to eventually fill withwater, the large flooding holes 3202 promote rapid, thorough flooding sothe nosecone section won't trap air that leaks away slowly, thuspreventing unpredictable, gradual altering the buoyancy of the URV 100.

Referring next to FIG. 33, a deck mounting rim 3300 is shown in oneembodiment of the invention. Shown are a foot 3302, the plurality of rimmounting holes 1304, a plurality of mounting rim screws 1902, two lowerdeck mounting holes 3304, three upper deck mounting holes 3308 and twodeck mounting screws 3306.

The deck mounting rim 3300 is approximately D-shaped, with the back ofthe D forming the foot 3302. The deck mounting rim 3300 may be made ofABS, polycarbonate, acrylic, or similar engineering plastic, or it maybe anodized aluminum, as required by the user. The deck mounting rim3300 is approximately 0.375″ thick in the out-of-plane direction, butmay vary depending as required to support the pressure vessel 104 asshown further below. The outside of a curved portion of the D-shape isgenerally semicircular and matches the outer perimeter of the end capmodule 3400. The deck mounting rim 3300 includes the standard rimmounting hole configuration generally arrayed around the hole of theD-shape. In the embodiment shown, nine rim mounting holes 1304 areincluded: two in the foot 3302, and seven in the curved portion. Theplurality of mounting rim screws 1902 are coupled to the deck mountingrim 3300 using the component mounting holes 1400.

The deck mounting rim 3300 also includes the two lower deck mountingholes 3304 located in outer portions of the foot 3302 of the D-shapewhere the curved portion of the deck mounting rim 3300 meets the foot3302, and oriented in the plane of the deck mounting rim 3300. The lowerdeck mounting holes 3304 are blind holes. The deck mounting screws 3306are coupled to the deck mounting holes.

The upper deck mounting holes 3308 are located in the center portion ofthe foot 3302, and pass through the width of the foot 3302. In thecurrent embodiment, three upper deck mounting holes 3308 are shown.

Optionally, the deck mounting rim 3300 may include the link strutmounting holes 1302 for coupling a chassis-mounted pressure vessel 104to the deck mounting rim 3300, as illustrated in FIG. 36.

Referring next to FIG. 34, the deck mounting rim 3300 is shown coupledto the end cap module 3400 of the pressure vessel 104. Additionallyshown are the mounting rim screws 1902.

The deck mounting rim 3300 is coupled to the component mounting holes1400 of the pressure vessel end cap 3400 using the mounting rim screws1902. When the end cap 3400 includes the external cavity, the interiorvoid of the D-shape is generally configured to allow access to theexternal cavity. The foot 3302 of the D-shape extends beyond the outerperimeter of the end cap module 3400.

Referring next to FIG. 35, pressure vessels 104 are shown coupled to adeck 3500 using the deck mounting rims 3300. Additionally shown are thedeck mounting screws 3306.

Each pressure vessel 104 includes the deck mounting rim 3300 coupled tothe end cap module 3400 as shown in FIG. 34. For each 104, the deckmounting rims 3300 are oriented so that the foot 3302 of each deckmounting rim 3300 is aligned in plane. The pressure vessel 104 is thenplaced with the foot 3302 of each deck mounting rim 3300 seated on thedeck 3500, i.e. the curved shape of the D-shape is pointing upward andthe pressure vessel 104 is supported horizontally between the two deckmounting rims 3300. The deck 3500 includes a plurality of deck holesconfigured to match the spacing of the deck mounting holes 3304 in thedeck mounting rim 3300. The pressure vessel 104 is then coupled to thedeck 3500 using the deck mounting screws 3306 passing through the deckholes and into the deck mounting holes of the deck mounting rim 3300.

Referring again to FIGS. 33-35, using the deck mounting rim 3300,pressure vessels 104 can be securely attached to a two dimensionalsurface, such as an underwater structure to which robotic componentsmust be added, such as the hull of a vessel or an underwater bottomcrawling robot. The deck mounting rim 3300 attaches to the dry end cap1212, the wet end cap, the cable manifold dry end cap 1208 or othermodule that includes the URVDS component mounting hole 1400configuration, being screwed into place with its curved edge generallyconcentric with the external portion 1308 of the end cap. The foot 3302includes two types of mounting holes: on the bottom are the lower deckmounting holes 3304, two threaded holes by which the deck mounting rim3300 can be screwed to the deck 3500 or other surface from below. Inaddition the deck mounting rim 3300 includes the upper deck mountingholes 3308 with clearance for screws or fasteners (typically 10-32screws) to pass through the upper deck mounting holes 3308 so that thedeck mounting rim 3300 can be securely fastened to the flat deck 3500.With deck mounting rims 3300 attached to end caps 3400 at the two endsof the pressure vessel 104, the pressure vessel 104 can be secured tothe flat surface.

Referring next to FIG. 36, a pressure vessel-chassis assembly 3600 isshown coupled to the deck 3500 using the deck mounting rims 3300. Shownare the deck 3500, two chassis-mounted pressure vessels 3602, thechassis 102, three deck-mounted pressure vessels 3604, the deck mountingrims 3300, the plurality of link struts 500, and the deck mountedscrews.

The three deck-mounted pressure vessels 3604 are coupled to the deck3500 as previously shown in FIG. 35. The chassis 102 is located abovethe deck-mounted pressure vessel 3604 and is coupled to and supported bythe plurality of link struts 500. The chassis 102 is coupled to andsupports the two chassis-mounted pressure vessel 3602.

Since the semicircular curved portion of the deck mounting rim 3300 ispenetrated with the seven threaded holes in the same manner as the endcap's link strut mounting holes 1302, link struts 500 can be secured tothe upper surface of the deck mounting rim 3300 as shown, so that if thedeck mounting rims 3300 and their pressure vessels 3604 are properlyspaced (the beam 204 width of the chassis system being used), rails 200might be attached to the deck mounting rim 3300. Note that link struts500 may also still be attached to the end caps 3400, so that their railclamps 208 are staggered with respect to the rail clamps 208 attached tostruts in the deck mounting rim 3300 so that when they are attached tothe rail 200 they can both attach to the rail 200 without interferingwith one another. This allows the chassis rail system with attachedpressure vessels 104 to be secured to the flat surface and built up asneeded by the user.

Printed Circuit Board Mounting System

Printed circuit boards (PCBs) are the predominant type of componenthoused in the pressure vessels 104. The PCB may be typically rectangularstandard off-the-shelf PCBs, or user designed circular PCBs 3700 to packmore densely into the pressure vessels 104 to minimize its length. TheURVDS has a flexible set of PCB mounting methods that work forrectangular or circular PCBs 3700, and which allow different boardgeometries to compatibly share the same pressure vessels 104 withoutinterference. These methods can be used with all of the types ofpressure vessels 104 end caps and dry links 2200.

In the present embodiment, the components that comprise the CircuitBoard Mounting System are:

1) Dry end caps 1212 or dry links; 2) Support Column Mounting Rings; 3)Support column rails 2906, 4) PCB Mounting Brackets 3800 and mountingplates 4002, 5) PCB Rail Mounting Clips 4200, 6) Commercially available4-40 threaded standoffs 3702.

As previously described, a feature specified in the URVDS architectureand shared among all modules is the set of twelve 4-40 tappedaxially-oriented component mounting holes 1400. In the presentembodiment, the component mounting holes 1400 form a 2″ diameter boltcircle axially aligned with the end cap axis.

Referring next to FIG. 37, an exploded view of the plurality of circularPCBs 3700 is shown for mounting to the dry end cap 1212. Shown are thedry end cap 1212, the circular PCBs 3700, the component mounting holes1400, the standoffs 3702 and the standoff fasteners.

In one embodiment, circular PCBs 3700 may be mounted directly to the endof any end cap 3400, link or other module that includes the standardcomponent mounting holes 1400 (for example, the support column). Thecircular PCBs 3700 are configured to almost slidably fit within theinterior of the tube 1100, with the center of the PCB aligned with thecenter of the tube 1100. The circular PCBs 3700 may have connectors thatpass wiring through the board, or may require another technique such asnotching the board to allow passage for wiring or cables 2604. Thecircular PCBs 3700 include perimeter holes located to match thecomponent mounting hole configuration. One or more PCBs may be coupledto the module by interposing internally threaded standoffs 3702 betweenthe circular PCBs 3700 and between the circular PCB 3700 and the linkmodule. In the example shown, three standoffs 3702 are used between eachelement, for a total of 9 standoffs 3702 used to couple 3 circular PCBs3700 to the dry end cap 1212. In one embodiment, male-to-femalestandoffs 3702 are used. In the exemplary URVDS, circular PCBs 3700 withdiameters between 2.2″ and 2.5″, and holes for #4 screws on a 1″ radiusare mounted to a link using 4-40 standoffs 3702. It will be appreciatedby those of ordinary skill in the art that a rectangular PCB 3900 mayalso be coupled to the link module as long as the rectangular PCB 3900(or other shape PCB) fits within the tube 1100 and includes enoughmounting holes in the configuration to match the component mountingholes 1400.

Referring next to FIG. 38, an exemplary rectangular PCB mounting bracket3800 in one embodiment of the present invention is shown. Shown arecomponent mounting holes 1400, a bracket notch 3802, two bracket legs3804, a bracket base and four flanges 3808.

The rectangular PCB mounting bracket 3800 is a general U-shape comprisedof flat plates and configured such that the bracket base 3806 of the Umounts to the standard component mounting holes 1400 of the module andthe bracket legs 3804 of the U-shape are generally parallel to thelongitudinal axis of the tube 1100. The bracket legs 3804 are generallyperpendicular to the bracket base 3806 and extending outward from themodule. The bracket base 3806 includes two holes configured to match thestandard component mounting hole spacing with one hole skipped (suchthat the component mounting holes 1400 are aligned horizontally withrespect to the bracket base 3806). The semicircular bracket notch 3802in the midpoint of the U-shaped bracket base 3806, on the bottom side,allows for access of the component mounting hole 1400 of the modulelocated between the component mounting holes 1400 of the bracket 3800when the bracket 3800 is coupled to the module. Each leg of the U-shapeincludes two flanges 3808, each flange 3808 including a hole configuredto receive a fastener for mounting the rectangular PCB 3900 to therectangular PCB mounting bracket 3800. The flange 3808 is orientedperpendicularly to the plane of the leg and extends outward (relative tothe U-shape) from a top of the leg in the embodiment shown. The flange3808 may alternately extend inward as required to match the location ofthe mounting holes of the PCB. The dimensions of the rectangular PBCmounting bracket 3800 are configure such that the flange holes match themounting hole locations and dimensions of the commercially availablerectangular PCB 3900. The rectangular mounting bracket 3800 may comprisea bent sheet metal such as aluminum, or may comprise cast plastic orother suitable material.

For typical commercially available rectangular PCBs 3900, e.g. aBeagleBoard Linux Board or a Raspberry Pi™ Linux Board, the rectangularPCB mounting bracket 3800 matches the standard rectangular PCB mountingholes, allowing the standard rectangular PCB 3900 to be used in theURVDS. The mounting bracket 3800 is coupled to the standard componentmounting holes 1400, allowing it to be coupled to any module includingthe component mounting holes 1400. The semicircular bracket notch 3802allows the mounting bracket 3800 to clear any support column rail 2906that might be present.

Referring next to FIG. 39, a perspective view of the plurality ofrectangular PCBs 3900 mounted to the dry end cap 1212 is shown. Shownare the rectangular PCB mounting bracket 3800, the dry end cap 1212, theflanges 3808, the standoffs 3702, and the fasteners.

The rectangular PCB mounting bracket 3800 is coupled to the dry end cap1212 or other suitably configured module with the compatible threadedfasteners inserted into the component mounting holes 1400 located in thebracket base 3806 and into the component mounting holes 1400 of the dryend cap 1212. The semicircular bracket notch 3802 faces towards theperimeter of the dry end cap 1212 and clears the component mounting holelocated between the component mounting hole 1400 locations, aspreviously described. Similarly to the mounting of the circular PCBs3700, the rectangular PCBs 3900 are spaced using the standoffs 3702. Thestandoffs 3702 are located at each corner of the rectangular PCB 3900,aligning with holes located in corners of the rectangular PCB 3900 andthe flanges 3808 of the rectangular PCB mounting bracket 3800. Thestandoffs 3702 are some combination of male-to-female or female threadedstandoffs 3702 such that the board stack is fastened together as a unitand mounted to the rectangular PCB mounting bracket 3800 with screws infemale standoffs 3702. In some embodiments, insulated washers areincluded between the mounting bracket 3800 and the board. The mountingbracket legs 3804 are generally oriented in the strong directionrelative to a weight of the rectangular PCBs 3900.

In some embodiments, rectangular and circular PCBs 3900 3700 may bemounted in the same tube 1100 when circular PCBs 3700 are mounted to oneend cap and the rectangular PCBs 3900 are mounted to the opposite cap.

Referring next to FIG. 40, an exploded view of an exemplary rectangularPCB mounting shelf 4000 and a mounting plate 4002 is shown. Shown arethe rectangular PCB mounting shelf 4000, the rectangular PCB mountingplate 4002, a plurality of mounting plate fasteners 4004, the firstmounting shelf leg 4006, a second mounting shelf leg 4008, and aplurality of shelf nuts 4010.

The mounting shelf 4000 is L-shaped, with the first leg 4006 of the Lsimilar in configuration to the bracket base 3806, i.e. including thetwo component mounting holes 1400 for coupling the shelf to the dry endcap 1212 or other suitable link and the semicircular bracket notch 3802for clearing the component mounting hole 1400 of the module. The secondleg 4008 of the L extends outward generally perpendicular to the firstleg 4006 and includes at least three holes for coupling the mountingplate 4002 to the mounting shelf 4000. The mounting plate 4002 is ofsimilar dimension to the rectangular PCB 3900 and includes corner holesfor receiving threaded fasteners at locations analogous to the flangeholes of the rectangular PCB mounting bracket 3800. The mounting plate4002 also includes three holes configured to align with the holes in thesecond leg 4008 of the mounting shelf 4000, and is coupled to themounting shelf 4000 with the mounting plate fasteners 4004 and shelfnuts 4010. The mounting plate 4002 coupled to the mounting shelf 4000forms the horizontal support for coupling the rectangular PCBs 3900 andstandoffs 3702 to the dry end cap 1212 or other suitable module.

The mounting shelf 4000 and the mounting plate 4002 can be made so thatusers need only make the flat mounting plate 4002 drilled out with holesto screw it to the mounting shelf 4000 and mounting holes for whateverrectangular PCB 3900 they have. This relieves the user of needing tohave sheet metal bending skill and equipment.

Referring next to FIG. 41, a perspective view of rectangular PCBs 3900coupled to the dry nosecone 2700 using the mounting shelf 4000 and themounting plate 4002 are shown. Shown are the dry nosecone 2700, themounting plate 4002, the mounting shelf 4000, the plurality of mountingplate fasteners 4004, the plurality of rectangular PCBs 3900, theplurality of component mounting holes 1400, and the plurality ofstandoffs 3702.

The mounting shelf 4000 and the mounting plate 4002 are shown coupledtogether with the mounting plate fasteners 4004 and the mounting shelf4000 is coupled to the internal portion 1306 of the dry nosecone 2700using the standard component mounting holes 1400 and accompanyingfasteners. As previously described, the alternating rectangular PCBs3900 and standoffs 3702 are coupled to the mounting plate 4002 using thestandoffs 3702.

Referring next to FIG. 42, the mounting clip 4200 in a first embodimentis shown. Shown are a clip U-shaped portion 4202, two prongs 4204, awasher 4206, a nut 4208, and a clip threaded fastener 4210.

The mounting clip 4200 comprises the generally U-shaped portion 4202(with the prongs 4204 of the U-shape oriented downward) including tworounded prongs 4204 configured to snap around the support column rail2906 (or other longitudinal rod member), coupling the mounting clip 4200to the support column rail 2906. A base of the U-shape is configured toallow for the nut 4208 to fit between the prongs 4204 at the base of theU-shaped portion 4202. The optional insulated washer 4206 is located onthe outside face of the base of the U-shaped portion 4202. The base ofthe U-shaped portion 4202 includes a hole for the clip threaded fastener4210, which passes through the washer 4206, base of the U-shaped portion4202 and the nut 4208, thus coupling the clip assembly together. In use,the PCB is coupled to the mounting clip 4200 between the head of thethreaded fastener and the washer 4206, thus coupling the PCB to thesupport column 2900 of the pressure vessel 104, as described furtherbelow.

In order to clip the PCB to the support column rails 2906 using themounting clips 4200, the spacing between the mounting clips 4200 mustmatch the distance between the support column rails 2906.

Referring next to FIG. 43, a second embodiment of the mounting clip 4200is shown. Shown are the U-shaped portion 4202, the clip threadedfastener 4210, the nut 4208, and the prongs 4204.

In the embodiment shown in FIG. 43, a head of the clip threaded fastener4210 is located between the prongs 4204 of the u-shape, with a shaft ofthe clip threaded fastener 4210 oriented in the upward direction. Thenut 4208 is coupled to the clip threaded fastener 4210 above the base ofthe U-shape. The base of the U-shape is configured to accommodate thehead of the clip threaded fastener 4210 between the prongs 4204 insteadof the nut 4208 as shown in FIG. 43. The prongs 4204 are shapedsimilarly the embodiment shown in FIG. 42, being configured to snap ontothe support column rail 2906. As with the embodiment shown in FIG. 42,in use the prongs 4204 are snapped onto the support column rail 2906,and the rectangular PCB 3900 is coupled to the mounting clip 4200 usingthe clip threaded fastener 4210 and the nut 4208. The embodiment shownin FIG. 43 may also include the optional insulated washer 4206.

Referring next to FIG. 44, a generic mounting plate 4400 with mountingclips 4200 is shown. Shown are the generic mounting plate 4400, fourmounting clips 4200, and a plurality of PCB mounting holes 4402.

The generic mounting plate 4400 including a grid of PCB mounting holes4402 may be used instead of coupling the rectangular PCB 3900 directlyto the mounting clips 4200 as shown below in FIG. 45. The mounting clips4200 are coupled to the generic mounting plate 4400 in locations toallow them to couple to the support column rails 2906. The rectangularPCB 3900 is then coupled to the generic mounting board holes usingstandoffs 3702 and threaded fasteners. The mounting clip 4200 holespacings of the generic mounting plate 4400 match the component mountingholes 1400 spacings, i.e., 1″, 1.414″, 1.732″, and 2.0″, or may becustom hole spacings.

Referring next to FIG. 45, an exemplary perspective view of coupling ofrectangular PCBs 3900 to the support column using the mounting clips4200 is shown. Shown are the support column rails 2906, the supportcolumn rings, the plurality of rectangular PCBs 3900, the plurality ofcircular PCBs 3700, the generic mounting plate 4400, the plurality ofstandoffs 3702, and the plurality of mounting clips 4200.

In one embodiment, one mounting clip 4200 is fastened to each corner ofthe rectangular PCB 3900 and each mounting clip 4200 is then snappedonto the appropriately spaced support column rail 2906. Multiplerectangular PCBs 3900 may be stacked using standoffs 3702 as previouslydescribed, with the suitable fastener length. This embodiment ispossible with off-the-shelf rectangular PCBs 3900 if the PCB mountingholes 4402 match one of the standard interior support column rail 2906spacings of 1.0″, 1.414″, 1.732″, or 2.0″, or may be custom holespacings.

In another embodiment, the generic mounting plate 4400 is coupled to thesupport column rails 2906 using the mounting clips 4200, and a pluralityof square PCBs 4500 are coupled to the generic mounting plate 4400 usingthe threaded fasteners and standoffs 3702.

The exemplary view shown in FIG. 45 also includes rectangular PCBs 3900coupled to the mounting bracket 3800, which is in turn coupled to thesupport column ring. Also shown are the plurality of circular PCBs 3700directly coupled to the opposite support column ring using standoffs3702, as previously described. The PCBs include notches as required toaccommodate the support column rails 2906.

Electrical Distribution System

Unlike land-based WiFi, networking of electronic components inunderwater robotic vehicles is handled almost exclusively by usingcopper wire (or fiber) as transmission medium. Almost all such networksuse standard off-the-shelf components and data communications protocolscommonly used on land: UTP Ethernet, RS-232, RS-422 or RS-485 serial,USB, SPI, I2C, or similar protocols that exist at the Data Link andhigher layers. These in turn use the standard star, bus, or(occasionally) ring ISO/OSI Physical Layer network cabling topologies incommon use. A means of implementing those physical layer wiring schemesbetween separate pressure vessels 104 is important to maintaining themodularity and usefulness that those proven ISO/OSI protocols offer. Inthe URVDS, the cable manifold system is used to provide connectionsbetween pressure vessels 104 that is adaptable to accommodate variedelectrical and communication components, major topologies, powersystems, and data communication protocols.

Referring next to FIG. 46, an exemplary pressure vessel system 4600 isshown. Shown are a portion of a main computer pressure vessel 4602, apressure vessel 0 4604, a pressure vessel 1 4606, a pressure vessel 24608, a sonar transducer pressure vessel 4610, a cable manifold link 14612, a cable manifold link 2 4614, a thruster pressure vessel 0 4616, athruster pressure vessel 1 4618, a plurality of electrical cables, aplurality of interior cables, and a plurality of sonar transducers 4620.

For clarity, the pressure vessel and other elements are shownindependent of the chassis 102 and are not meant to represent anoperable pressure vessel orientation. Additionally, only the cablemanifold portion of the main computer pressure vessel 4602 and the sonarcontroller pressure vessel are shown for clarity, omitting the tube1100, end cap 3400, PCBs 3700 3900 4500 and other elements that arenecessary for operation of the URV 100.

In the exemplary pressure vessel system 4600 shown, the main computerpressure vessel 4602 includes a main computer system for controlling theURV 100. The main computer system is electrically coupled to peripheralsystems (such as a sonar controller system) through the cable manifoldlink 1 4612 of the main computer pressure vessel 4602. The plurality ofcables 1214 coupled to the cable manifold link 1 4612 couple the maincomputer system to the thruster pressure vessel 0 4616, the thrusterpressure vessel 1 4618, the cable manifold link 2 4614, and the pressurevessel 0 4604. Additional cables 1214 couple pressure vessel 1 4606 andpressure vessel 2 4608 to pressure vessel 0 4604 in series. Ports on thecable manifold link 2 4614 couple the sonar transducers 4620 to theplurality of cable manifold 2 ports, with external cables 1214interposed between the sonar transducers 4620 and the cable manifold 2ports.

As previously described, the pressure vessel can accommodate waterproofoutlets for electrical and/or communication cables 1214 at each end cap,and may also include the cable manifold link 1210 or end cap, wheremultiple electrical/communication/power connection ports are arrayedaround the module. As shown in FIG. 46, the main computer pressurevessel 4602 includes the cable manifold link 1 4612, which connects tofour separate pressure vessel via cables 1214 coupled to the connectionports: pressure vessel 0 4604, thruster pressure vessel 0 4616, thrusterpressure vessel 1 4618, and the sonar transducer pressure vessel 4610.The interior cables 2604 are coupled to the connection ports on aninterior side of the main computer pressure vessel 4602, and are coupledto electrical, power and communication components as required (notshown).

The Sonar transducer pressure vessel 4610 also includes the cablemanifold link 1210, which receives the cable 1214 from the main computerpressure vessel 4602. The sonar transducer pressure 4610 vessel alsouses the connection ports 2300 to provide necessary connections for theplurality of sonar transducers 4620.

The pressure vessel 0 4604 is coupled in series to the pressure vessel 14606, which is turn is coupled to the pressure vessel 2 4608, via cables1214 exiting at the end caps of the pressure vessel. In addition to startopologies implemented with the cable manifold, bus or ring topologiesare easily implemented between pressure vessels 104 using two end caps3400 with cable glands and connectors to daisy-chain multiple pressurevessels 104 for implementing bussed networks such as I2C, or RS-422.

Cable manifold links 1210 and cable manifold dry end caps 1208 arepreferably used for implementing star wiring when a large number ofelectrical connections need to fan out from the single pressure vessel104 to several pressure vessels 104. As previously described, the cablemanifold module 1210 1208 incorporates two o-ring seals 1106 to connecttwo pressure vessels 104 together and an opening which allows directelectrical wiring between pressure vessel 104 sections. It also has thetwelve link strut mounting holes 1302 for receiving link struts 500 usedto mount the pressure vessel 104 to the chassis 102. But it alsoincludes four, eight, or sixteen threaded port holes 2400 forcommercially available waterproof electrical connectors. One pressurevessel 104 can thus have up to 16 easily maintained electrical cables1214 passing from it to other vessels 104 which can be disconnected atwill.

The port inserts 2302 are not function specific. They simply attach theinternal cable's 2604 wires, pin for pin, to the external electricalconnection and the mating port insert 2302 connector. Thus the ports2300 can be wired independently, all having the same wiring pinout orhaving different pinouts. For example, the main computer pressure vessel4602 could terminate with the cable manifold link 1 4612 and have onecable 1214 wired for UTP Ethernet to pass commands and data to theuser's computer at the surface, six cables wired for USB, I2C, SPI, oranalog signals going to various sensors 4800 in other pressure vessels104 and six cables wired for RS-232 extending to motor controllers ineach of six thrusters.

If additional connections are required, more cable manifolds 1210 1208are easily added, or a custom manifold with the required number of ports2300 is easily built.

The cable manifold 1208 1210 is manufactured with the threaded holes2400 and O-ring mating surfaces machined to fit the particular brand ofcommercially available underwater port insert 2302, such as thoseproduced by Ikelite, Fischer, SeaCon, Impulse, or watertight cableglands from HexSeal and other companies. Custom cable manifolds can bemade that handle more than one company's port inserts 2302, e.g., fourFischer port inserts 2302 with M1×12 metric threads, and eight Ikeliteport inserts 2302 with ½″-20 UNRF threads, etc. This is useful whenexisting equipment with different port inserts 2302 have to be mated tothe single pressure vessel 104.

The electrical, communication and power systems may be controlled by anysystem desired by the user, as the URVDS accommodates a variety ofoptions for mounting various circuit boards and as shown, accommodates alarge variety of electrical/power/communication connections betweencomponents. Control systems may be centralized, as shown in FIG. 1, withhigh-level system control residing in the controller in the maincomputer pressure vessel 4602, or system control may be decentralized,with control residing in various auxiliary pressure vessels 2602.

One implementation can support in-situ programming access to everymicrocontroller in the URV 100 via a multiplexed UART and multiplexedSPI bus, so low level controllers can be reprogrammed and improvedwithout removing them from the URV system. It is important in the URVDSto avoid unnecessarily taking the URV 100 apart or breaking theintegrity of URV watertight seals. Typical land-based practices forreprogramming microcontrollers in a distributed control architecture isto open the URV 100 up, connect a programming component to programmingport on the microcontroller in question, reprogram it, then re-seal theURV 100. In an underwater system, sealing the URV 100 is a painstakingprocess and each time the URV 100 is opened is an opportunity for asealing error leading to the pressure vessel 104 flooded with seawaterand a catastrophic failure requiring replacement of all the exposedelectronics. But in any development system, re-programming is a frequenttask, one to be encouraged if the system is to be improved. The URVDSfully supports in-situ programming access to every computer andmicrocontroller in the system without opening up the URV 100.

Referring next to FIG. 47, an exemplary centralized electrical controlsystem is shown. Shown the main computer pressure vessel 4602 includingthe plurality of ports 2300, a main controller system 4702, aUTP-ethernet system 4704, a motor controller system 4706, a batterysystem 4708, a user control system 4710, a plurality of thruster motors4712, two cameras 4714, an interface system 4716, a voltage regulatorsystem 4718, and a plurality of motor amplifiers 4020.

In the centralized control system, the main computer pressure vessel4602 includes the computer, electrical, power and communication systemsrequired to operate components and/or modules external to the maincomputer pressure vessel 4602, for example the motors in thrusterpressure vessel 0 4616 and thruster pressure vessel 1 4618 shown in FIG.46.

The main computer vessel includes the main controller system 4702, theUTP-ethernet system 4704, the motor controller system 4706, the batterysystem 4708, the interface system 4716, and the voltage regulator system4710. The main controller system 4702, the motor controller system 4706,the interface system 4716 and the UTP-ethernet system arecommunicatively and/or electrically coupled to the plurality of ports2300 included in the main computer pressure vessel 4602.

The user control system 4710, the thruster motors 4712, and the cameras4714 are located outside of the main computer pressure vessel. Theseexternal components 4710 4712 4714 are electrically and/orcommunicatively coupled to the systems in the main computer pressurevessel 4602 through the ports 2300.

The main controller system, in conjunction with the UTP-Ethernet system,is coupled to and in communication with the internal interface system4716, the user control system 4710, and the cameras 4714. The interfacesystem 4716 communicates with and controls the motor controller system4706. The motor controller system 4706 then communicates with andcontrols the external thruster motors 4712.

Referring again to FIG. 47, a 6-DOF URV system centralizes high-levelcontrol in an on-board embedded controller system. The centralizedcontroller system scheme distributes low level control of sensors andactuators (motor control, etc.) among subordinate controller systems,each dedicated to a particular control task for modularity and ease ofdevelopment. An on-board Ethernet switch provides UTP-Ethernet accessfrom the user control system 4710 to all Linux computers, and a serialport mux scheme provides UART access to the main controller system 4702and all subordinate control systems. This scheme allows a large degreeof software transparency: full access to every controller system and forin situ programming and diagnostics through either Ethernet, UART, or acontroller system's SPI bus.

One example of a main controller system 4702 includes sixmicrocontrollers, one for each of six thrusters needed for a true 6-DOFURV. Each one supplies PWM pulses to the motor controller system 4706including 6 motor amplifiers 4020 to control the thruster motors 4712.

The interface system 4716 is the interface between the main controllersystem 4702 and the motor controller system 4706. A Gumstix Controllerplugs into this board, and its communication ports and general purposeI/O lines are buffered and routed to the appropriate motor control lines(SPI port and UART, and mux control lines) on the motor controllersystem 4706.

Another important feature of the interface system 4716 is a serialswitch which is the key to easy management of control over controllersystems throughout the entire network of current and future devices.

Referring next to FIG. 48, the cable manifold with directly connectingsensors 4800 is shown. Shown are the cable manifold link 1210, the tube1100, the plurality of sensors 4800, a plurality of cable manifoldports, and a plurality of sensor housings 4802.

In lieu of the cable-connection system shown in FIG. 1 for couplingsensors 4800 to the URV 100, the cable manifold port 2300 may be used todirectly mount sensors 4800 or other peripherals. The sensor 4800 may befitted to and electrically coupled to the sensor housing 4802 that hasbeen configured to plug into and couple with the cable manifold port.This allows easy mounting and easy access to their wiring through apressure vessel wall 2800. It will be appreciated that other types oflinks may be fitted with and configured to receive the sensors 4800 orperipherals. In the embodiment shown, the electrical connectors areIkelite connectors. The mating peripheral housing 4802 is configured toelectrically couple with the electrical connector of the cable manifoldlink 1210. As an example, the housing 4802 shown in FIG. 49 includes apocket for the pressure sensor 4800 (Measurement Specialties Corp. partnumber 86-015G-C). The sensor housing 4802 can be fabricated with thesame interface as a standard connector such as the Ikelite connector,allowing it to be mounted to the cable manifold port 2300. The sensor4800 may be secured to the sensor housing 4802 by inserting a c-ring5002 into a groove in the top of the housing 4802 after the sensor 4800is placed in the sensor housing 4802 (similarly to the dry end cap 1212implementation shown in FIG. 49).

Referring next to FIG. 49, a sensor cable port 4900 installed in the dryend cap 1212 is shown. Shown are the dry end cap 1212, the sensor cableport 4900, the sensor housing 4802, and the sensor 4800.

In yet another embodiment, the tubular portion of the dry end cap 1212may include the sensor cable port 4900 installed in a base of thetubular portion. The sensor cable port 4900 is configured to interfacewith the sensor 4800 similarly to the cable manifold ports 2300. Thesensor housing 4802 is then coupled to the sensor cable port 4900 in thedry end cap 1212. In this configuration, the wet nosecone 3200 may alsobe coupled to the dry end cap 1212, enclosing the sensor 4800, to allowfor exposure of the sensor 4800 to ambient water but still protect thesensor 4800 from impact.

Referring next to FIG. 50, an exploded view of the dry end cap 1212including an end cap hole 5000 in one embodiment of the invention isshown. Shown are the dry end cap 1212, the sensor 4800, the tube 1100,and the end cap hole 5000.

The internal portion 1306 of the dry end cap 1212 distal to the tube1100 may include the end cap hole 5000 configured to receive the sensor4800 and c-ring 5002 without use of the sensor housing 4802 as shown inFIGS. 48 and 49. In the embodiment shown in FIG. 50, the dry end cap1212 is configured with the end cap hole 5000 to receive a MeasurementSpecialties 86-015G-C Pressure Sensor and the sensor 4800 also includesa groove configured to receive the retaining C-clip. If required, signalconditioning circuitry can be mounted on the dry end cap 1212 (asdiscussed above) and the end cap 1212 becomes a dedicated sensor module.

Referring next to FIG. 51, a power management system 5100 coupled to thedry end cap 1212 is shown in one embodiment of the present invention.Shown are the dry end cap 1212, a power management circuit board 5102,the power management system 5100, a fuse 5104, a DPDT relay 5106, a reedswitch 5108, an external power connector 5200, a system power busconnector 5112, and a battery connector 5114.

The power management system 5100 comprises the power management circuitboard 5102 including the magnetically operated reed switch 5108, thefuse 5104, the DPDT electromechanical relay, and the connectors 51125200 to form the system to perform common power related functions. Thepower management system 5100 is also coupled to an internal battery 5208(not shown, in one embodiment the battery 5208 may be 2-4 nickel metalhydride 7.2V battery packs in series for 28.8V) via the batteryconnector 5114. The power management circuit board 5102 is coupled tothe dry end cap 1212 using the standard connection configuration. Alongitudinal axis of the reed switch 5108 is oriented parallel to thelongitudinal axis of the pressure vessel 104.

The power related functions performed by the power management system5100 may include an On-Off Switch function, connecting the on-boardbattery 5208 to a power bus of the URV 100 when power is switched on,charging the battery 5208 from an external power source, or powering theURV 100 while simultaneously charging the battery 5208. The operation ofthe reed switch 5108 is described further below in FIGS. 53-55.

When switched on, the on-board battery 5208 is connected to the powerbus of the URV 100. When switched off, the battery 5208 is connected topin 1 of the three-pin connector for charging and the URV power bus isconnected to pin 2 of the three-pin connector for attachment to aseparate external power source such as a lab power supply to allowcurrent limited testing.

Referring next to FIG. 52, a schematic diagram for the power managementsystem 5100 as shown in FIG. 5 is shown. Shown are the external powerconnector 5200, a v_charge pin connection 5202, v_ext_power pinconnection 5204, a first ground pin connection 5206, the DPDT relay5106, the reed switch 5108, the fuse 5104, the battery 5208, the systempower bus connection, a v_sys pin connection 5210 and a second groundpin connection 5212, a DPDT switch off position 5214, and a DPDT switchon position 5216.

The exemplary power management system 5100 manages On/OFF switching andthe interface to on-board batteries. When the reed switch 5108 isunactivated, the DPDT relay 5106 is in the off position 5214. When noexternal power is connected, this results in the v_ext_power pinconnection 5204 being connected to the v_sys pin connection 5210. Thev_ext_power pin connection 5204 is the connection to an external powersource, and the v_sys pin connection 5210 supplies power to the URV 100.Since there is no external power, no power is transferred to the systemand the URV 100 is off.

When an external power source is connected to the circuit via both thev_charge and the v_ext_power pins 5202 5204, but the reed switch 5108remains unactivated, the DPDT relay 5106 remains in the same offposition 5214. The circuit then connects v_charge 5202 to the battery5208, charging the battery 5208, and connects v_ext_power 5204 to v_sys5210, powering the URV 100 while the battery 5208 is being charged.

When the reed switch 5108 is activated, it activates a magnetic coilproximate to the DPDT relay 5106, throwing both DPDT switches to the onposition 5216. As a result, v_charge 5202 and v_ext_power 5204 aredisconnected from the circuit, and the battery 5208 is connected tov_sys 5210, thus powering the system from the battery 5208 anddisconnecting from the external power source.

In operation, the power management system 5100 utilizes the reed switch5108 triggered by a switch magnet 5302 housed in the magnetic switchsleeve 5300 on the outside of the pressure vessel 104 without usingconventional switches which penetrate the pressure vessel 104. Themagnetic sleeve 5300 and activation of the reed switch 5108 is describedbelow in FIGS. 7-9.

Referring next to FIGS. 53-55, the magnetic switch sleeve 5300 for thepower management system 5100 is shown in one embodiment of the presentinvention. Shown are the switch magnet 5302, a screw notch 5304, thereed switch 5108, the dry end cap 1212, a first tube mounting screw5306, a second tube mounting screw 5308, and the tube 1100.

The power management circuit board 5102 is shown coupled to the dry endcap 1212 and the tube 1100 is coupled to the dry end cap 1212 using tubemounting screws 1108 as previously described. In this embodiment, tubemounting screw 1108 heads protrude past the perimeter of the tube 1100.The power management system 5100 includes the magnetically operated reedswitch 5108, located proximate to a side of the tube 1100. The magneticswitch sleeve 5300 comprises a plastic cylinder configured to slidablyfit around the tube 1100. The magnetic switch sleeve 5300 includes thescrew notch 5304 in the longitudinal direction of the magnetic switchsleeve 5300 which extends from the end of the magnetic switch sleeve5300 proximate to the power management system 5100 to a location nearthe midpoint of a magnetic switch sleeve length. The screw notch 5304includes a round portion near the end of the magnetic switch sleeve 5300proximate to the power management system 5100, the screw notch 5304being configured to snap-fit onto one tube mounting screw 1108 head,thus coupling the magnetic switch sleeve 5300 to the dry end cap 1212.The screw notch 5304 may terminate in another rounded portion toalleviate stress in the plastic.

The magnetic switch sleeve 5300 also includes the switch magnet 5302embedded in the magnetic switch sleeve 5300 in the location such thatthe switch magnet 5302 may align with the reed switch 5108 below whenthe sleeve is snapped to one of the tube mounting screws 1108. Theswitch magnet 5302 may be a rare earth magnet or any other type ofmagnet capable of triggering the reed switch 5108. In FIG. 53, themagnetic switch sleeve 5300 is shown slid onto the tube 1100 but not yetsnapped onto one of the tube mounting screws 1108.

In the position shown in FIG. 54, the magnetic switch sleeve 5300 hasbeen slid upward towards the dry end cap 1212 and snapped to and therebycoupled to the first tube mounting screw 5306. The position of the firsttube mounting screw 5306 is such that the reed switch 5108 is notdirectly below the switch magnet 5302 when the magnetic switch sleeve5300 is snapped to the first tube mounting screw 5306. The reed switch5108 thereby remains open and in the off configuration.

As shown in FIG. 55, the magnetic switch sleeve 5300 has been snapped toand coupled to the second tube mounting screw 5308. In that position,the switch magnet 5302 is aligned with and below the reed switch 5108,closing the reed switch 5108 to the on configuration.

Since the placement of the circuit board mounting holes on the dry endcap 1212 are specified per the standard connection configuration (aspreviously described in the pressure vessel section) as always alignedwith the tube mounting holes 1300, it is possible to design circuitboards whose components align with other mechanical features, such asthe reed switch 5108.

Referring next to FIG. 56, the dry end cap 1212 including an externalpower and charging port 5600 is shown. Shown are the dry end cap 1212,the tube 1100, the magnetic switch sleeve 5300, the switch magnet 5302,the external power and charging port 5600 and a water-tight cap 5602.

The external power and charging port 5600 is mounted to the exteriorbase of the tubular portion of the dry end cap 1212 or other compatiblelink end. The external power and charging port 5600 is electricallycoupled to the external power connector 5200 of the power managementsystem 5100. The external power and charging port 5600 is configured toexternally couple to a charging cable for charging the internal battery5208 and/or operation from an external test bench supply. When thecharging port is not in use, the water-tight cap 5602 including at leastone o-ring seal 1106 is coupled to and seals the charging port againstwater intrusion.

Propulsion System

Referring next to FIG. 57, an exemplary URV 100 with a sixdegree-of-freedom (DOF) propulsion system is shown. Shown are thechassis 102, two auxiliary thruster pressure vessels 5702, two centralthruster pressure vessels 5700, a plurality of inline propeller modules6000, and a plurality of lateral propeller modules 6302.

The URVDS propulsion system provides modules which can be used to buildat least three types of thruster pressure vessels 106: an inlinethruster pressure vessel 6100, a lateral thruster pressure vessel 6300,and an inline rudder thruster pressure vessel 6500 which provide,respectively, axial thrust (relative to the longitudinal or y-directionof the URV 100), lateral thrust, or axial thrust with pitch, yaw andlimited roll steering. As with all other end caps in the URVDS, pressurevessels 104 including propulsion modules may be coupled to the chassis102 using the link strut system previously discussed.

The exemplary propulsion system shown in FIG. 57 includes two centralthruster pressure vessels 5700 each central thruster pressure vessel5700 including two lateral propeller modules 6302 configured to providethrust and/or rotation in a direction in the x-z plane, i.e. orthogonalto the longitudinal axis of the pressure vessel. Two auxiliary thrusterpressure vessels 5702 each include the inline propeller module 6000 forproviding thrust in the y-direction, i.e. in the direction of thelongitudinal axis of the pressure vessel. The inline rudder thrusterpressure vessel 6500 (not shown) may additionally include a ruddersystem as described further below.

Referring again to FIG. 57, the inline and lateral propeller modules6000 6302 are typically used in orthogonal pairs to provide up to sixdegrees of freedom for high three-axis maneuverability for applicationslike precise station keeping or obstacle avoidance in chaotic waterconditions such as surge and surf. This capability is useful for bothhuman controlled tele-operated systems or for URVs 100 under autonomouscontrol.

The URVDS demonstrates the ability to integrate into URV 100 thrustersystems built from opportunistically obtained DC motors 5800. Thisallows the user to tailor the thruster system's speed and torque to thedemands of the mission, and also allows the user to effect field repairof the propeller module 6000 6302 by replacing the motor 5800 with onethat is similar but not an exact replacement. This makes field repairsin places far away from well stocked supply depots easier.

Referring next to FIG. 58, an exemplary motor assembly 5810 is shown inexploded view. Shown are the motor 5800, a bulkhead disk 5802, aplurality of bulkhead screws 5804, a motor shaft 5808, and a motorcoupling 5806.

The generally cylindrical motor 5800 is coupled to the bulkhead disk5802 using the plurality of bulkhead screws 5804 such that the axis ofthe motor 5800 and a center of the bulkhead disk 5802 align, centeringthe motor 5800 in the housing such that the motor shaft 5808 can engagea magnetic clutch (as described further below). DC motors 5800, brushedor brushless (with appropriate controllers), can be fitted to thebulkhead disk 5802 and motor coupling 5806 to standardize the interfaceto the magnetic clutch. The bulkhead disk 5802 is configured to coupleto the motor 5800 and a magnetic clutch end cap 5900. The motor coupling5806 may be a standard ½″ or ⅝″ Lovejoy coupling for use with theexemplary magnetic clutch, or any other suitable type of motor coupling5806, for example a Oldham coupling.

Motors 5800 of varying dimensions may be coupled to the magnetic clutchend cap 5900 by varying the configuration of the bulkhead disk 5802.This makes motors 5800 with a much large range of sizes, voltages andperformance specs (often from the surplus market at very low cost) usein tailoring their thrusters to their mission requirements.

Referring next to FIG. 59, the magnetic clutch end cap 5900 is shown inone embodiment of the invention. The magnetic clutch end cap 5900 isshown looking towards the end of the pressure vessel. Shown are a clutchhousing 5902, a clutch end cap housing 5904, two o-rings, a plurality ofhousing screws 5906, and the motor coupling 5806.

At the proximate end of the magnetic clutch end cap 5900 (i.e. the endlocated inside the tube 1100) the Motor coupling 5806 is coupled to themotor coupling 5806 portion shown previously in FIG. 58, rotationallycoupling the motor shaft 5808 with a clutch shaft, which will bedescribed further in FIG. 4. The clutch housing 5902 is coupled to thebulkhead disk 5802 using suitable fasteners. The distal end of themagnetic end cap is coupled to the propeller module, as describedfurther below.

Referring next to FIG. 60, a longitudinal cross-section of the magneticclutch end cap 5900 coupled to a propeller housing is shown. Shown arethe clutch housing 5902, an end cap housing, the Motor coupling 5806, aclutch magnetic disk 6006, an external magnetic disk 6004, a propellerhousing, an end cap shaft 6014, an external shaft 6010, and a propeller.

The clutch housing 5902 is a generally tubular shape including aradially outward-facing flange at an end of the clutch housing 5902distal to the propeller housing. An interior space of the clutch housing5902 is configured to receive the end cap shaft 6014, which runs throughthe center of the clutch housing 5902 and is coupled to the Motorcoupling 5806 at the clutch housing 5902 end distal to the propellerhousing and coupled to the clutch magnetic disk 6006 at an end proximateto the propeller housing. The end cap shaft 6014 is coupled to theclutch housing 5902 to allow for rotational freedom but is fixed againsttranslation.

The clutch magnetic disk 6006 is a disk shape and is coupled to the endcap shaft 6014 such that a center of the disk aligns with the axis ofthe end cap shaft 6014. The clutch magnetic disk 6006 includes fourmagnets embedded in the clutch magnetic disk 6006 proximate to theperimeter of the magnetic clutch end cap 5900 and with a uniform anglebetween each magnet. In one embodiment, the magnets are “rare earth”Neodymiun magnets. Two magnets are aligned with the north pole facingupwards, and two magnets are aligned with the south pole facing upwards,with similarly oriented magnets alternating around the perimeter. Inother embodiments 6 magnets, 8 magnets, or other multiples of two may beused. In yet another embodiment, the magnetic disk comprises a singlemagnet with each hemisphere comprising north and south polesmanufactured into the magnet.

The end cap housing is a cylinder shape with a central cylindrical voidlocated in the end of the end cap housing proximate to the clutchhousing 5902 and configured to receive the tubular portion of the clutchhousing 5902. The housing screws 5906 couple the clutch housing flangeto a wall of the tubular portion pf the end cap housing. When the clutchhousing 5902 is coupled to the end cap housing, the clutch magnetic disk6006 is located close enough to the exterior face of the end cap housingproximate to the propeller housing such that the clutch magnetic disk6006 is sufficiently attractive to the external magnetic disk 6004.

The end cap housing also includes an exterior shoulder configured toreceive the pressure vessel tube 1100, and two o-rings in theconfiguration as shown previously for the dry end cap 1212.

An end cap housing end proximate to the propeller housing includes acylindrical void configured to receive the propeller housing and alignthe external shaft 6010 and the external magnetic disk 6004 with theclutch magnetic shaft and end cap shaft 6014.

The propeller housing is configured for the specific propeller type,which in FIG. 60 is the inline propeller 6012. The propeller housingincludes a central approximately cylindrical cavity for receiving theexternal magnetic disk 6004 and the external shaft 6010. As with theclutch housing 5902, the external magnetic disk 6004 is coupled to theexternal shaft 6010, and the external shaft 6010 is coupled to thepropeller housing to provide rotational, but not translational,movement.

The external magnetic disk 6004 is configured similarly to the clutchmagnetic disk 6006. The propeller housing is coupled to the end caphousing using end cap mounting holes and screws as previously describedfor typical end cap connections. When the propeller housing is coupledto the end cap housing, the magnets of the external magnetic disk 6004and the clutch magnetic disk 6006 attract, coupling the end cap shaft6014 to the external shaft 6010 for rotational movement. Thus, when themotor shaft 5808 rotates, the rotation is transferred to the end capshaft 6014 via the Motor coupling 5806, and rotation of the end capshaft 6014 is transferred to the external shaft 6010 via the magneticcoupling of the clutch magnetic disk 6006 and the external magnetic disk6004. The strength of the magnets and the distance between the disksmust be configured to provide enough magnetic attraction to allow theshafts to rotate at the desired speed without breaking the magneticattraction between the magnetic disks.

Referring again to FIGS. 59 and 60, the magnetic clutch system transmitstorque from the motor 5800 to the propeller via the magnetic clutchcomprised of the clutch magnetic disk 6006 and the external magneticdisk 6004, instead of using a shaft which penetrates the pressure vessel104 and is sealed with shaft seals. Shaft seals all wear over time andrequire continuous vigilance to avoid leaks that are major sources offailure, particularly in seawater, where contact with electronics mayresult in catastrophic failure. The magnetic clutch allows the interiorof the pressure vessel 104 to remain sealed, and allows for changing ofthruster end caps without affecting the interior portion of the pressurevessel 104.

Additionally, the magnetic clutch system provides additional safety forthe user. While providing sufficient torque to drive the propellerthrough water, the magnetic clutch will slip should the propeller becomeentangled or strike a carelessly placed hand. Thus, even at full speed,the user can grab the propeller and it will slip rather than cut theuser.

All propeller modules of the URVDS are configured to mate with themagnetic clutch end cap 5900.

Referring next to FIG. 61, an exploded view of a portion of the inlinethruster pressure vessel 6100 is shown. Shown are the motor assembly5810, the inline propeller module 6000, the magnetic clutch end cap5900, the propeller housing, a motor mounting plate 6104, the inlinepropeller 6012, and a propeller shroud 6106.

The motor assembly 5810 includes the motor 5800, the bulkhead and themotor coupling 5806, as previously described. The motor mounting plate6104 is coupled to the end of the magnetic clutch end cap 5900 proximateto the motor assembly 5810. The inline propeller 6012 is rotationallycoupled to the external shaft 6010 (not shown) such that the axis of thepropeller is aligned with the longitudinal axis of the thruster pressurevessel, providing force along the longitudinal axis. The toroidalpropeller shroud 6106 is coupled to the propeller housing such that theprotector ring encases the propeller edge perimeter.

Referring next to FIG. 62, a portion of the assembled inline thrusterpressure vessel 6100 is shown. Shown are the motor assembly 5810, theinline propeller module 6000, the magnetic clutch end cap 5900, aninline propeller housing 6008, the motor mounting plate 6104, the tube1100, the inline propeller 6012, and the inline propeller shroud 6106.

As assembled, the motor mounting plate 6104 is coupled to the bulkheadof the motor assembly 5810 using screws or other suitable fastener. Aspreviously described, the propeller housing is coupled to the magneticclutch end cap 5900, which also brings the magnetic disks into proximityand magnetically couples the magnetic disks of the magnetic clutch,providing continuous torque along the shafts and turning the inlinepropeller 6012. The tube 1100 is coupled to the magnetic end cap aspreviously described for the typical end cap, and is coupled to anotherdry end cap-type module on the other tube 1100 end (not shown).

In use, the inline thruster pressure vessel 6100 produces thrust alongthe axis of the propeller housing, as is commonly practiced. In mostcircumstances the inline thruster pressure vessel 6100 will provide thethrust along the URV's 100 primary direction of travel.

Referring next to FIG. 63, a portion of the assembled lateral thrusterpressure vessel 6300 is shown. Shown are the motor assembly 5810, thelateral propeller module 6302, the magnetic clutch end cap 5900, alateral propeller housing 6306, the motor mounting plate 6104, a lateralpropeller 6304 and the tube 1100.

The lateral thruster pressure vessel 6300 is assembled similarly to theinline thruster pressure vessel 6100, with the substitution of thelateral propeller module 6302 for the inline propeller module 6000. Thelateral propeller housing 6306 comprises a cylindrical shape including acylindrical penetration perpendicular to the axis of the cylinder,located near a midpoint of the lateral propeller housing 6306. The endof the lateral propeller housing 6306 proximate to and coupling to themagnetic clutch end cap 5900 is configured to mate with the magneticclutch end cap 5900 similarly to the inline propeller housing 6008. Theportion of the lateral propeller housing 6306 proximate to the to themagnetic clutch end cap 5900 also includes voids for accommodating theexternal magnetic disk 6004 and the external shaft 6010. The lateralpropeller 6304 is rotationally coupled to the housing such that thepropeller is located inside the lateral propeller housing 6306 with theaxis of the lateral propeller 6304 aligned with the centers of thepenetration, i.e. perpendicular to the longitudinal axis of the lateralthruster pressure vessel 6300. The lateral propeller 6304 is coupled tothe external shaft 6010 such that the rotation of the external shaft6010 rotates the lateral propeller 6304.

The lateral thruster pressure vessel 6300 provides maneuvering thrustthat is perpendicular to the longitudinal axis of the lateral thrusterpressure vessel 6300. By mounting the propeller rotated around thelongitudinal axis, thrust can be directed vertically, horizontally, orany angle in 30 degree increments, while still presenting a drag profilein the URV's primary direction of travel that is only a fraction of thatobtained by simply mounting conventional in-line thrusters orthogonallyto the main axis of travel.

It will be appreciated that the modules of the inline thruster pressurevessel 6100 and the lateral thruster vessel are identical, with theexception of the propeller module. The inline thruster pressure vessel6100 may be changed to the lateral thruster pressure vessel 6300 simplyby removing the inline propeller housing 6008 and replacing it with thelateral propeller housing 6306, and vice versa. Other housings includingthe standard connection configuration and the magnetic clutch mayalternately be coupled to the thruster pressure vessel 106.

Referring next to FIG. 64, a cross-sectional view of the lateralpropeller module 6302 is shown. Shown are the external magnetic disk6004, a bevel gear shaft 6400, a propeller shaft 6402, the lateralpropeller 6304, a bevel gear, two lateral propeller shaft support rods6406, a driving spur gear 6408, a driven spur gear 6410, and theexternal shaft 6010.

The external shaft 6010 includes the driving spur gear 6408, which ismeshed with the driven spur gear 6410. The driven spur gear 6410 isaligned with and coupled to the bevel gear shaft 6400. The bevel gearshaft 6400 terminates in the bevel gear. The bevel gear is coupled tothe propeller shaft 6402.

In one embodiment of the present invention, the propeller shaft 6402 issupported by lateral propeller shaft support rods 6406 spanning acrossthe cylindrical penetration at the exterior of the lateral propellerhousing 6306. The lateral propeller 6304 is coupled to the propellershaft 6402 at approximately the midpoint of the penetration.

In operation, the magnetic clutch rotates the magnetic shaft and thedriving spur gear 6408. The driving gear rotates the driven spur gear6410, transferring the rotation to the bevel gear shaft 6400. The bevelgear shaft 6400 is coupled to the propeller shaft 6402 via the bevelgear, which translates the rotational axis from a longitudinal axis tothe radial axis required by the later propeller orientation.

Referring next to FIGS. 65 and 66, the inline rudder thruster pressurevessel 6500 is shown in elevation and in section. Shown are the tube1100, the motor assembly 5810, a rudder module magnetic clutch end cap,the inline propeller housing 6008, a plurality of rudders 6504, themotor coupling 5806, the end cap shaft 6014, a plurality of ruddershafts 6600, the propeller shaft 6402, the magnetic clutch, the inlinepropeller, a servo assembly 6602, and the propeller shroud 6106.

The inline rudder thruster pressure vessel 6500 uses a modified magneticclutch end cap (an inline rudder magnetic clutch end cap 6502) thatincorporates additional elements for rotation of rudders 6504 whichextend outward from the perimeter of the inline rudder magnetic clutchend cap 6502. Coupled to the end cap shaft 6014 is the servo assembly6602, which includes four servos. Rudder shafts are rotationally coupledto the servo assembly 6602 and extend through the perimeter of therudder module magnetic clutch end cap housing, including a watertightseal around the shafts while still permitting rotation as shown in FIG.67. Each rudder 6504 is coupled to the corresponding rudder shaft 6600.In the embodiment shown, four rudders 6504 are equally spaced around theperimeter of the inline rudder magnetic clutch end cap 6502, but othernumbers of rudders 6504 may be used as desired.

The end cap shaft 6014 of the rudder module magnetic clutch end cappasses between the four servos, and is long enough to span the distancebetween the motor 5800 and the magnetic clutch on the other side. Theservo output is normally 180 degrees of rotation at 19 oz-in of torque.Each servo shaft drives a 4:1 reduction gear that turns the rudder shaft6600 which passes through the inline rudder magnetic clutch end cap 6502through an o-ring rotary seal and attaches to the rudder 6504,delivering 45 degrees of rotation at roughly 60 oz-in.

The end cap shaft 6014 extends to the end of the inline rudder magneticclutch end cap 6502 proximate to the propeller, where it is coupled tothe inline propeller module 6000.

Referring again to FIGS. 65 and 66, a common design for autonomous URVs100 that are designed for long-range data-gathering operation along apre-programmed route is to have the single long thruster pressure vesselterminated with the single inline propeller 6012 and two to four rudders6504 for steering rather than relying upon multiple orthogonallyoriented thrusters for maneuvering as is typical in tele-operated URVs100. When operating in open obstacle-free water this scheme tradesun-needed turn-in-place maneuverability for increased range byminimizing the drag profile. The URVDS supports this with the inlinerudder thruster pressure vessel 6500.

Servos included in the servo assembly 6602 are readily commerciallyavailable and can be driven by any of several commercially availablecircuit boards that receive position commands via RS-232, SPI, I2C, andwhich output standardized servo control PWM signals to multiple servos.These signals are well described in the literature and customizedcircuit boards that provide equivalent signals are easily built. Anexemplary version uses a circuit board with a single microcontrollersuch as an Atmel ATMega48 to convert RS232 coded position commands toPWM signals on four output lines to the four servos.

While two actuators controlling two rudders 6504 each (coupled together)on opposite sides of the robot would be sufficient to control yaw andpitch maneuvering, having four independent rudders 6504 more options forcontrol by enabling the URV 100 to control roll about its longitudinalaxis. For example, the tendency for the URV 100 to roll that is impartedby a single propeller turning in the water can be counteracted, or theURV 100 can actively roll, for example to point an instrument such asthe camera in different directions.

While the inline and lateral propellers are typically used in dedicatedpressure vessels 103 on URVs 100 with multiple pressure vessels 104, theinline rudder magnetic clutch end cap 5602 and inline propeller module6000 typically terminate the single pressure vessel 104 which houses allcontrol electronics, power supplies, and payloads for long rangeuntethered autonomous operation. This design configuration is typifiedby torpedo-form autonomous vehicles.

Referring next to FIG. 67, a cross-section of a rudder shaft mount 6708is shown. Shown are the inline rudder magnetic clutch end cap 6502, therudder shaft 6600, a plurality of rudder shaft mounting screws 6700, aninner o-ring 6702, an outer o-ring 6704, and an outer bearing 6706.

The rudder shaft mount 6708 is a generally tubular structure including alateral flange configured to seat on the exterior of the inline ruddermagnetic clutch end cap 6502 when the rudder shaft mount 6708 isinserted in a hole in an exterior wall of the inline rudder magneticclutch end cap 6502. The rudder shaft 6600 passes through the ruddershaft mount 6708 before exiting the inline rudder magnetic clutch endcap 6502. A plurality of fasteners, for example the rudder shaftmounting screws 6700, couple the rudder shaft mount 6708 to the inlinerudder magnetic clutch end cap 6502. The rudder shaft mount 6708includes a perimeter notch proximate to the interior of the end cap forreceiving the outer o-ring 6704. The rudder shaft mount 6708 alsoincludes an inner notch proximate to the exterior of the end cap forreceiving the inner o-ring. The rudder shaft mount 6708 is alsoconfigured to receiving the tubular outer bearing 6706 where the ruddershaft 6600 exits the rudder shaft mount 6708.

The lower o-ring, which seals a joint between the rudder shaft mount6708 and the inline rudder magnetic clutch end cap 6502, is a staticseal preventing water ingress around the mounting. The upper o-ring,which seals a joint between the rudder shaft mount 6708 and the ruddershaft 6600, is a rotary seal configured to rotate only throughapproximately 22.5 degrees, and rotates only when the rudder 6504changes angle (i.e. fairly infrequently) (when the rudder 6504 changesangle), thus the upper o-ring can be considered to be a static seal withits characteristically high reliability, rather than a rotary seal.

Buoyancy Management System

Referring next to FIG. 68, a cylindrical float buoyancy module 6800 isshown. Shown are a cylindrical float 6802, the link struts 500 and therail clamps 208.

Cylindrical float 6802 may be made of polystyrene foam with a ⅛″ thicklayer of epoxy resin as a coating. In the embodiment shown each end ofthe cylindrical float 6802 terminates in a nosecone shape. The diameterof the cylindrical float 6802 is typically chosen such that thecylindrical float buoyancy module 6800 may be coupled to parallelchassis rails 200. The cylindrical float buoyancy module 6800 includestwo link struts 500, one proximate to each end, which are embedded inthe cross-section of the cylindrical float 6802 and protrude on eachside. Ends of the link struts 500 are coupled to the rail clamp 208. Thecylindrical float buoyancy module 6800 may then be coupled to the rails200 of the chassis 102 as previously described in the chassis section.It will be apparent to those skilled in the art that otherconfigurations of embedded link struts 500 and cylindrical floatbuoyancy module 6800 lengths may be used.

Referring next to FIG. 69, the URV 100 including a syntactic foambuoyancy module 6900 is shown. Shown are the chassis 102, the pressurevessel 104, the rail clamps 208, the link struts 500, and the syntacticfoam buoyancy module 6900.

The syntactic foam buoyancy module 6900 in the embodiment shown is arectangular shape including a circular cut-out near the center. Thesyntactic foam buoyancy module 6900 also includes embedded link struts500. The syntactic foam buoyancy module 6900 of FIG. 69 includes sixlinks struts embedded so that one end remains within the syntactic foambuoyancy module 6900. The protruding end of the link strut 500 iscoupled to the rail clamp 208, which is coupled to the rail 200 aspreviously shown.

Syntactic foam is available in formulations to provide buoyancy at anyocean depth without crushing, and is easily machined into any shape.Since syntactic foam buoyancy modules 6900 don't rely upon cylindricalshape to withstand pressure they can be made in flat-sided volumes suchas the rectangular volume of FIG. 69 or more intricate shapes whenneeded. The syntactic foam buoyancy module 6900 of FIG. 69 includes thecircular cut-out above the URV's vertical thruster to permit free flowof water through the propellers.

Another buoyancy module 108 method is to simply use empty pressurevessels 104 either alone or by adding additional length to existingpressure vessels 104 that contain other components. The amount ofbuoyancy gained is easily derived from the volume of the tube 1100, andthe water it displaces. The 3″ diameter acrylic tube 1100 with a ¾″thick wall yields 0.166 lbs of buoyancy per inch of empty tube 1100length, almost exactly 1 lb per 6″ of tube 1100 (excluding its mountinghardware). This is also easier for the user to build in the field sinceit only requires cutting the pressure vessel tube 1100 to the lengthrequired for the amount of flotation needed, and then using existing endcaps to seal it. Pressure vessels 104 used for buoyancy need not becompletely empty. A few light components such as circuit boards may beincorporated and cabled into the main system at the user's discretion.

Referring next to FIG. 70, a perspective view of a ballast module 7000is shown. Shown are a first ballast 7002, a second ballast 7004, aballast notch 7006, and a plurality of ballast screws 7008.

The ballast modules 7000 are comprised of lead encased in rubber orplastic and include two generally half-cylindrical parts: the firstballast 7002 and the second ballast 7004. The first ballast 7002 and thesecond ballast 7004 are coupled together using the ballast screws 7008,and form a generally cylindrical shape when coupled together. A spacemay be left between the first ballast 7002 and the second ballast 7004in the coupled position. The flat sides of the first ballast 7002 andthe second ballast 7004 include the longitudinal ballast notch 7006 suchthat the rail 200 may fit in the notches when the first ballast 7002 iscoupled to the second ballast 7004.

While re-positioning the buoyancy modules 108 allows great control oftrim, sometimes the best solution will be a combination of both buoyancyand ballast. The repositionable ballast modules 7000 complement thebuoyancy modules 108, providing trimming weights typically ranging from0.25 lbs to 0.5 lbs to correct small errors in trim.

Referring next to FIG. 71, two ballast modules 7000 are shown attachedto the chassis 102. Shown are a rail ballast 7104, a beam ballast 7102and the chassis 102.

The rail ballast 7104, is shown coupled to the rail 200 of the chassis102, and the beam ballast 7102 is shown coupled to the beam 204 of thechassis 102. The ballasts may be repositioned by loosening the ballastscrews 7008 and sliding the ballast along the rail 200 or beam 204, ormay be removed by removing the screws entirely and then recoupling theballast in another location on the chassis 102.

The beam 204 can be positioned anywhere along the rail 200, providingfore-aft trim, and the ballast module 7000 can be positioned from sideto side along the beam 204 for providing fine adjustment of side to sidetrim whenever differences in cabling or attached sensors 4800 oraccessories create a list to the side. Thus a pound or two of ballastcan be positioned precisely anywhere in the horizontal plane containedby the rails 200. While their main intent is to be used as temporarytrim while adjusting the overall trim of the URV 100 under development,they can be permanently installed at the user's discretion. Thedimensions of the rectangular center opening for the rail 200 are suchthat the weight can be screwed down onto either rails 200 or (typicallythinner) beam 204 or post 206 rods.

Normally the buoyancy modules 108 of all types are mounted upon strutsthreaded for rail clamps 208 so that the buoyancy modules 108 can beeasily moved along the rails 200 to adjust trim; e.g., if the URV 100 isnose-heavy in the water, its buoyancy modules 108 can be slid forwardalong the rails 200 or the URV's 100 heavier masses can be slidbackwards until the masses and buoyancies are balanced.

The rail chassis system allows great freedom to position a URV's 100negative and positively buoyant buoyancy modules 108 or pressure vessels104 to give a metacentric height in accordance with the URV's 100required function. For example, on the URV 100 that is primarily aremote camera platform it may be advantageous to have a steadyhorizontal attitude to give a camera viewer a stable horizontal image toprovide greater visual orientation in a chaotic visual environment. ThisURV 100 would benefit from a high MH, placing its buoyancy modules 108at the top of the vehicle and its heavier elements, motors 5800,batteries, etc. lower on the chassis 102. But on another URV 100 thepositive and negative elements may be balanced about its central plane,giving a low (or zero) MH, facilitating pitch and roll maneuvers thatmay be useful if its camera is frequently pointed upward or downward orat odd angles as it might be during a pipe inspection.

Referring next to FIGS. 71A-71D, rebalancing of the URV 100 whileassembled is shown. Shown are the URV 100, the added pressure vessel7104, and the buoyancy module 7106.

In FIG. 71A, the URV 100 is underwater in a balanced position such thatthe longitudinal axes of the pressure vessels 104 are approximatelyhorizontal. In FIG. 71B, the added pressure vessel 7104 has been coupledto one side of the URV 100 using the chassis system as previouslydescribed, unbalancing the URV such that the longitudinal axes are nolonger horizontal. In FIG. 71C, the added pressure vessel 7104 has beenmoved along its attached rail 200 such that the URV 100 is rebalancedand the longitudinal axes are again horizontal. In FIG. 71D, analternate means of rebalancing the URV of FIG. 71B is shown. In FIG.71D, the buoyancy module 7106 is moved along its attached rail 200 suchthat the URV 100 is rebalanced.

Referring again to FIGS. 71A-71D, mass and trim change heavilyinfluences the speed of the design cycle for underwater vehicles. Forany unrestrained submerged object, gravity will align its center ofbuoyancy (CB—specifically, the center of gravity of the water the objectdisplaces) vertically above its center of gravity (CG).

The URV must be balanced front to back and side to side by insuring thatthe axis between the CB and CG is perpendicular to the intendedhorizontal plane of the resting vehicle. Any offset in thatperpendicular alignment will result in the URV 100 listing in the waterto an extent proportional to the extent of the misalignment.

Any new pressure vessel that is added or subtracted or re-positioned andthat is not either neutrally buoyant or positioned with its own CB andCG axis co-linear with the vehicle's main CB-CG axis will requirecompensating repositioning of buoyancy to realign the the URV's 100horizontal orientation.

On both commercially available and experimental, researcher-built URVs100 this balance is typically achieved by calculating the weights andbuoyancies of the pressure vessels 104 in advance and positioning themwithin the chassis with some small measure of adjustability to provide amargin of error. The calculations require considerable skill. If theyare in error (or a new pressure vessel 104 that substantially alters thebalance needs to be added) and the masses must be repositioned,substantial re-design of the chassis 102 is often needed. Even an errorof a few inches of offset will cause a noticeable list. The more oftenpressure vessels 104 need to be added or subtracted from the URV 100 themore often this time-consuming process will have to be carried out by aknowledgeable engineer.

Having the chassis 102 composed of parallel rails 200 allows the variousindividual pressure vessels 104 and buoyancy modules 108 to berepositioned forward and backward along the full length of the chassisrails 200 until the positively and negatively buoyant elements areexactly balanced. This gives the user the ability to quickly and easilycompensate for even large new loads. Even the inexperienced user can dothis quickly and easily using direct observation rather thancalculation. By simply placing the URV 100 in water and sliding thepressure vessels or buoyancy modules 108 along the chassis rails 200until they balance and the chassis 102 floats level in the water (addingnew buoyancy 108 or ballast modules 7000 if needed), and then securingthem in place, the operation of balancing the URV is made as easy andintuitive as using a balance beam scale.

Exemplary URVs Using the URVDS System

The modularity and the recombinability of the URVDS provides fordevelopment of URVs 100 with a vast range of scale, complexity andmission capability. Shown here are examples of URVs 100 developed usingthe URVDS.

Referring next to FIG. 72, a plurality of URVs is shown: a one-cell URV7200, a two-cell URV 7202 and a three-cell URV 7204 along with a diver1004 for scale. These small-scale URVs 7200 7202 7204 may include thereconfigurable chassis system or the permanent welded chassis 102.Adding more cells lets the user easily add additional pressure vessels104 for sensors 4800, computation, buoyancy, batteries, etc. as needed.

Referring next to FIG. 73, a more complex three-cell URV is shown,including ten pressure vessels 104 coupled to the chassis 102. The URVDSallows for a wide range of numbers of pressure vessels 104 attached tothe chassis 102, allowing for the system to be configured for any userrequirement.

Small Scale URV Systems

Referring next to FIG. 74, shown is an exemplary small-scale AutonomousUnderwater Vehicle (AUV) 7400 in one embodiment of the URVDS. The AUV7400 includes the URVDS pressure vessel system by includes no externalchassis 102 and is configured for untethered autonomous operation. Allmaneuvering is controlled by a plurality of tailfins 7402. The AUV 7400depends upon forward motion, with water flowing over their fins, tomaneuver. The AUV 7400 is excellent for long distance travel butincapable of station-keeping (maintaining a hover in one spot).

Referring next to FIG. 75, an exemplary pipe inspection URV 7500 isshown. The pipe inspection URV 7500 includes a long, narrow one-cellchassis. The pipe inspection URV 7500 includes one inline thruster (atrear), two vertically oriented lateral thrusters and two horizontallyoriented lateral thrusters for 5 degrees of freedom, forward, sideways,and vertical motion with pitch and yaw. This would make it a very agilerobot in conditions of confined spaces that required fitting throughsmall openings but also required avoiding contact with walls, even inturbulent conditions, such as a forensic or archaeological dive on ashipwreck.

Large Scale URV Systems

The same chassis geometry principles apply to larger frames, allowinglarger thrusters, more batteries and heavier loads. As with the smaller4.5″-grid frames described above, the chassis 102 can be extended tohandle more pressure vessels 104 by stacking cells.

Referring next to FIG. 76, an exemplary heavy-lift salvage URV system isshown lifting a piece of heavy underwater salvage 7602. Shown are afirst URV 7604, a second URV 7606, two lift bags 7608, the salvage 7602,and the plurality of divers 1004.

The heavy-lift salvage URV 7600 assists salvage divers 1004 recoveringlarge heavy objects from the seafloor. As previously known in the art,one or more divers 1004 would attach inflatable lift bags 7608 to theheavy salvage object 7602 and maneuver it through the water by manuallyinflating or deflating the lift bag 7608 with air from their scuba tanksto control vertical movement, and swimming along pushing the object.With lift bags 7608 supplying typically able to supply thousands ofpounds of lift, this is a tricky operation with large forces involved;and errors or mishaps such as a knot slipping loose or a severed cablebetween lift bags 7608 and object may be catastrophic.

The exemplary heavy-lift salvage URV 7600 is built on a heavy weldedfour-cell chassis 102 built on the 9″ grid unit 712 with 1″ diameterrails 200. Note the use of both 3″ and 6″ diameter pressure vessels 104,allowed by simply adjusting the strut lengths and using larger railcollars to match the larger frame size. The users would first build thereconfigurable chassis 102 to mount pressure vessels 104 onto to developthe robot and to test and confirm its viability, then build thepermanent welded chassis 102 if long term use was desired.

The robot controls the filling and venting of the large lift bags 7608via an electronically valved air tank using feedback from its depthsensors 4800 to control depth. The lift bags can deliver typically 500to 1000 lbs of buoyancy each to lift heavy objects off the bottom andmove them under command of nearby salvage divers 1004. This allows thesalvage divers 1004 a safe stand-off distance from a dangerous operationas well as precise digital control over rates of ascent and positioning.Ultrasonic positioning beacons on each URV could allow each URV tolocate its position relative to other robots and allow coordinated‘swarm’ behaviors to lift larger objects. This would allow closelycoordinated lifting in dark or murky waters where human divers 1004would be unable to see each other or communicate for coordinated effort.

Referring again to FIG. 10 the exemplary IMAX® camera support URV 1000is shown. Shown are the IMAX® camera 1002, the support URV 1000, and thediver 1004.

The URVDS reconfigurable chassis elements make it possible to buildlarge complex and rigid space frames and integrate robotic componentsinto their structures. From a few simple elements, the chassis for arobot of arbitrary size and complexity can be built to fit customizedapplications. Thus, a robotic ‘overcoat’ or exoskeleton can be wrappedaround large, difficult to maneuver underwater objects.

The exemplary IMAX® camera support URV 1000 is configured to support the1300 lb IMAX® Underwater Camera 1002 system, used to createhigh-definition underwater movies in panoramic format for the popularIMAX® Theatres. Although it is neutrally buoyant in water, the housedcamera's 1300 lb inertial mass and high drag make it operable in onlythe most benign underwater conditions, normally requiring two divers1004 to manipulate it, making it difficult to aim and follow fastswimming sea creatures. The system is impossible for even strong divers1004 to swim with against ocean currents as small as one knot, andconditions of strong surf or surge make its shifting 1300 lb mass toodangerous for operators to be near.

Wrapping the camera system 1002 in the robotic exoskeleton URV 1000 withinline and lateral thrusters for 6-degree-of-freedom maneuvering andaccelerometers and gyroscopes for stabilization would eliminate thosedifficulties, providing precise, autonomous or joystick-controlledself-propulsion, rapid and precise camera pan and tilt, and full camerastabilization even in the presence of chaotic current, surf and surge.The camera 1002 could then be driven via a joystick and ethernet tetherfrom a surface vessel or by the diver 1004 swimming alongside the camera1002 with a waterproof joystick. Used with an ultrasonic positioningsystem, it would enable complex underwater tracking shots to be madewith the complete repeatability for multiple takes that camera operatorson land enjoy.

One standard cell and trapezoidal cell form the basic space framepressure vessel chassis 900. As with small-scale chassis 102, the IMAXCamera chassis 900 consists of only the five typical chassis elements:1″ diameter×4′ long rails 200, 9″ posts 206, 15.588″ (9×(tan 60))″ beams204, and 0.18″ braces 202, all 0.75″ diameter, and the rail clamps 208that join the elements.

Thrusters, batteries, computer, sensors 4800 and buoyancy elements aremounted on the chassis 900. The chassis 900 could easily be extended andadapted to provide a place for the diver 1004/cameraman to ride (or betowed) behind the camera 1002, making the system a manned underwatercamera platform that could give the diver 1004/cameraman more precisecontrol and faster camera movement than divers 1004 could provide bypushing the camera 1002.

For production quantities of such a roboticized camera system URV 1000the welded steel or aluminum chassis 900 would be made. But duringprototyping, the reconfigurable chassis system would allow rapid designiterations allowing faster and more frequent experimental verificationor rejection of design changes required to perfect the permanent chassisthan could be obtained by constantly cutting and re-building the weldedprototype chassis.

Other Robotic Applications

The similar robotic exoskeleton chassis 102 could be quickly built toaccommodate standard oceanographic data collection tools like a SeabirdSBE-32 Carousel Water Sampler. The Water Sampler, normally deployed froma ship via a tether cable, collects 24 water samples either autonomouslyor on operator command. It could be configured as a roboticfree-swimming sampler, capable of autonomously taking samples fromseveral different locations and depths along a pre-programmed route.This could allow a single ship to drop several units, each independentlycollecting samples over many days, then recover them, rather than havingthe ship committed to managing one tethered sampler at a time, stayingon station for several days, then repeating the multi-day process atseveral locations. Since research vessel operations cost tens ofthousands of dollars per day, this could multiply the effectiveness ofresearch trips while achieving great cost savings.

While the invention herein disclosed has been described by means ofspecific embodiments, examples and applications thereof, numerousmodifications and variations could be made thereto by those skilled inthe art without departing from the scope of the invention set forth inthe claims.

What is claimed is:
 1. An underwater pressure vessel system, comprising:a dry end cap comprising a generally cylindrical internal portionincluding at least one groove extending around a perimeter of theinternal portion, the at least one groove located proximate to a firstend of the dry end cap and configured for receiving an o-ring seal; atleast one o-ring seal coupled to the cylindrical body and seated in theat least one groove; a generally cylindrical external portion concentricto the internal portion and located distal to the first end, wherein adiameter of the external portion is greater than a diameter of theinternal portion, and wherein an end of the external portion distal tothe internal portion is a second end of the dry end cap; a plurality ofcomponent mounting holes included in the first end of the internalportion, the component mounting holes arrayed in a circle proximate tothe perimeter of the internal portion and oriented parallel to alongitudinal axis of the dry end cap, the component mounting holesconfigured for coupling of a component to the dry end cap; a pluralityof link strut mounting holes including in the external portion of thedry end cap, the link strut mounting holes arrayed around a perimeter ofthe external portion and oriented radially with respect to the externalportion, the link strut mounting holes configured to couple to a linkstrut; and a plurality of tube mounting holes arrayed around theperimeter of the internal portion, oriented radially with respect to theinternal portion, and located between the at least one o-ring and theexternal portion, wherein the plurality of tube mounting holes areconfigured for coupling to a pressure vessel tube.
 2. The underwaterpressure vessel system of claim 1, wherein the external portion istubular.
 3. The underwater pressure vessel system of claim 2, whereinthe second end of the dry end cap further comprises a plurality of rimmounting holes arrayed in circle proximate to the perimeter of theexternal portion, the plurality of rim mounting holes oriented parallelto the longitudinal axis, the plurality of rim mounting holes configuredto couple to a rim.
 4. The underwater pressure vessel system of claim 3,further comprising a tubular rim concentrically coupled to the secondend of the dry end cap, the tubular rim including the plurality of rimmounting holes, the rim including a diameter smaller than the diameterof the external portion and including the plurality of tube mountingholes arrayed in a circle around the perimeter of the rim.
 5. Theunderwater pressure vessel system of claim 4, wherein the dry end cap isa first dry end cap, further comprising: a second dry end cap; a tubularend cap collar coupled to the second dry end cap, the end cap collarincluding an internal shoulder, wherein a first end of the end capcollar is above the shoulder and a second end of the end cap collar isbelow the shoulder, the end cap collar further comprising the pluralityof tube mounting holes located in a perimeter of the end cap collarproximate to the first end, the end cap collar further comprising theplurality of rim mounting holes located in the shoulder of the end capcollar, wherein the second end of the end cap collar is coupled to asecond end of the second dry end cap, and wherein the first dry end capis coupled to the second dry end cap by coupling the end cap collar tothe rim.
 6. The underwater pressure vessel system of claim 2, the secondend of the dry end cap further comprising a plurality ofradially-oriented strain relief grooves across the second end.
 7. Theunderwater pressure vessel system of claim 1, wherein the dry end capincludes at least one cable hole extending through the dry end cap andconfigured to allow a cable to pass through the dry end cap.
 8. Theunderwater pressure vessel system of claim 1, wherein the externalportion further comprises a plurality of cable port holes arrayed aroundthe perimeter of the second end, the cable port holes configured toreceive a waterproof electrical port insert, and wherein the internalportion is tubular such that a cable passing through the cable port holeexits through the first end of the dry end cap.
 9. The underwaterpressure vessel system of claim 1, wherein the internal portion is afirst internal portion, further comprising: a second internal portionconfigured to match the first internal portion, the external portioninterposed between the first internal portion and the second internalportion, the dry end cap further including a continuous longitudinalbore.
 10. The underwater pressure vessel system of claim 9, the externalportion further comprising a plurality of cable port holes arrayedaround the perimeter of the external portion, the cable port holesconfigured to receive a waterproof electrical port insert.
 11. Theunderwater pressure vessel system of claim 2, wherein the internalportion of the dry end cap includes a tubular portion forming aninternal cavity configured to receive a clutch housing, and furthercomprising: the clutch housing coupled to the internal portion of thedry end cap, the clutch housing including an end cap shaft configured torotationally couple to a motor, the end cap shaft coupled to the clutchhousing to allow rotation of the end cap shaft within the clutchhousing, an end cap magnetic disk concentrically coupled to an end ofthe end cap shaft proximate to the external portion, the end capmagnetic disk including at least four magnets embedded in the end capmagnetic disk proximate to the perimeter of the end cap magnetic disk,wherein the at least four magnets are aligned with opposite poles facingupwards.
 12. The underwater pressure vessel system of claim 11, furthercomprising: a propeller module configured to couple to the externalportion, the propeller module comprising: a propeller housing includinga void and the plurality of tube mounting holes in the perimeter of thepropeller housing such that the propeller housing is coupled to theexternal portion using a plurality of fasteners in the plurality of tubemounting holes; an external shaft passing through the void androtationally coupled to the propeller housing; an external magnetic diskconcentrically coupled to an end of a propeller shaft proximate to theexternal portion, the external magnetic disk including at least fourmagnets embedded in the external magnetic disk proximate to a perimeterof the end cap magnetic disk, wherein the at least four magnets arealigned with opposite poles facing upwards, whereby the end cap magneticdisk and the external magnetic disk are magnetically coupled such thatrotation of the end cap shaft causes rotation of the external shaft. 13.The underwater pressure vessel system of claim 12, further including apropeller coupled to the external shaft.
 14. The underwater pressurevessel system of claim 1, wherein the dry end cap is a first dry endcap, and further comprising: a pressure vessel comprising: a tubeincluding the plurality of tube mounting holes proximate to each end ofthe tube, wherein a first dry end cap internal portion is inserted intoa first end of the tube; a second dry end cap wherein a second dry endcap internal portion is inserted into a second end of the tube, wherebya watertight internal cavity is formed in the pressure vessel.
 15. Theunderwater pressure vessel system of claim 14, further comprising: achassis; a plurality of link struts coupled to the plurality of linkstrut mounting holes and to the chassis.
 16. The underwater pressurevessel system of claim 14, further comprising: a power assemblyincluding an electrical circuit including a power source and a reedswitch, the power assembly coupled to the first end of the first dry endcap such that the power assembly is contained within the pressurevessel; a sleeve configured to fit over the tube proximate to the firstdry end cap, the sleeve configured to move between a first position anda second position with respect to the power assembly, the sleeveincluding a magnet, such that when the sleeve is in the first positionthe magnet aligns with the reed switch and the reed switch is activated,and when the sleeve is in the second position the magnet does not alignwith the reed switch and the reed switch is unactivated.
 17. Theunderwater pressure vessel system of claim 16, further comprising afirst headed mounting screw and a second headed mounting screw coupledto the plurality of tube mounting holes proximate to the first dry endcap, and the magnetic sleeve further comprising a screw notch configuredto couple to a screw selected from the group consisting of a first screwand a second screw, wherein coupling the magnetic sleeve to the firstscrew locates the magnetic sleeve in the first position, and whereincoupling the magnetic sleeve to the second screw locates the magneticsleeve in the second position.
 18. The underwater pressure vessel systemof claim 14, wherein the tube is a first tube, further comprising: asecond tube interposed between the first tube and the first dry end cap;a tubular wet link interposed between the first tube and the secondtube, the wet link including a wet link internal portion, a wet linkexternal portion, the plurality of tube mounting holes in the perimeterof the wet link internal portion, the plurality of link strut mountingholes in the perimeter of the wet link external portion, a plurality ofwet link rim mounting holes in an end of the external portion andarrayed in a circle proximate to the perimeter of the external portion,the plurality of wet link rim mounting holes oriented parallel to thelongitudinal axis; a tubular mounting rim interposed between the wetlink and the first tube, the mounting rim including the plurality oftube mounting holes in a perimeter of the mounting rim and the pluralityof rim mounting holes oriented in a longitudinal direction and passingthrough the mounting rim, whereby the mounting rim is coupled to the wetlink using the rim mounting hole and the mounting rim is coupled to thefirst tube using the tube mounting holes.
 19. The underwater pressurevessel system of claim 1, further comprising: a pressure vesselcomprising: a tube including the plurality of tube mounting holesproximate to each end of the tube, wherein the internal portion of thedry end cap is inserted into a first end of the tube and coupled to thetube using a plurality of fasteners in the tube mounting holes; atubular wet link coupled to a second end of the tube, the wet linkincluding a wet link internal portion matching the configuration of theinternal portion and including the at least one o-ring groove and atleast one o-ring seal, and a wet link external portion matching theconfiguration of the external portion, the wet link internal portionincluding the plurality of tube mounting holes, the wet link externalportion including the plurality of link strut mounting holes, the wetlink further including a continuous longitudinal bore, the wet linkinternal portion inserted into a second end of the tube and coupled tothe tube using the plurality of fasteners in the tube mounting holes.20. The underwater pressure vessel system of claim 19, furthercomprising: a wet nosecone coupled to the external portion of the wetlink, the wet nosecone including the plurality of tube mounting holes inan end of the wet nosecone proximate to the wet link, the wet noseconefurther including a plurality of flooding holes in an end of the wetnosecone distal to the wet link, the flooding holes configured to allowfluid flow through the flooding holes.
 21. The underwater pressurevessel system of claim 1, wherein the second end of the dry end cap is aparabolic nosecone shape.